thoughts of a late night axolotl

CanoScan 9550F: “Unable to open TWAIN source”

Paul Coddington — Sat, 17 Jan 2009 00:00:00 +0100

You may receive the following error message when you try to import an image from your scanner into your graphics application:

“This application has failed to start because rmslantc.dll was not found. Re-installing the application may fix this problem.”

“Unable to open TWAIN source.”

This problem occurs when the system path environment variable exceeds the maximum character length expected by the CanoScan driver.

The system path is a list of folders, separated by semicolons, that identifies which folders the system should search when looking for executable files. Although 2048 characters are permitted, the CanoScan driver fails when the system path is between 700 and 800 characters.

Many applications append their installation folders to the system path, and it is not uncommon to see system paths exceeding 1000 characters in length.

A quick workaround is to prefix the CanoScan TWAIN folder to the system path. If this does not resolve the problem, it may be necessary to determine experimentally which path components can be safely removed.

For application developers, the system path length can be significantly reduced by removing all references to command line compilers, libraries and utilities. A task-specific command prompt shortcut can be added to the Start Menu, extending the system path as required using a batch file to modify the command prompt environment.

Windows Genuine Advantage Update (KB905474)

Paul Coddington — Fri, 05 May 2006 00:00:00 +0100

A Windows Update distributed across Australia last night has erroneously disabled my workstation.

“The validation process could not be completed because the validation control is unable to read the product key stored on this computer. We are unable to verify whether your copy of Windows is genuine.”

When the Windows Genuine Advantage (WGA) application fails with an internal error, it aggressively declares the operating system to be counterfeit by default. Subsequent logins are delayed by a countdown timer and reminders appear in the taskbar notification area.

Out of curiousity, I clicked the Get Genuine button that was presented to me while waiting for the login timeout to complete. My copy of Windows was immediately deactivated and I was taken to a web site which failed to load. The site would not allow me to proceed any further, declaring Windows “has not been activated”. It seemed odd that a web site designed to remedy a problem should depend on the problem being already solved in order to function correctly!

Reactivating Windows from my system administrator account succeeded, although this required an undocumented step which may confuse some users confronted by this issue.

As KB905474 is considered a critical update, it is downloaded and installed automatically unless Automatic Updates are disabled (not recommended). I should also mention that this batch of updates forced a timed reboot of my system which could not be cancelled. Work was lost while taking a phone call and time was wasted investigating “counterfeit” warnings.

The phrase “victim of counterfeiting” seems somewhat ironic in this context.

Solution

Permission errors are usually not that hard to track down. The problem is determining where the product key is located and finding the time to complete the task. The Microsoft Sysinternals tool set has some excellent utilities that can be used to analyse and resolve such problems.

Even so, I decided to Google the problem again, 10 hours after the fact, to see what had developed. As it turns out, someone had already posted a fix.

The problem is that the WGA application requires write access to a data file that it installs without regard for permissions that might be required to allow ordinary users access. I would hope that another edition of this update will be released in the near future to address this oversight, and that Microsoft would also ensure that anyone who follows on-screen instructions to obtain a genuine copy of Windows is not confronted by a broken web site.

For those who need this fix, the solution is to grant non-administrative users change access to this folder:

%AllUsersProfile%\Application Data\Windows Genuine Advantage\data

Security Implications

One of the unfortunate side-effects of this dysfunctional update is that any malicious person desiring to deactivate Windows XP computers by remote attack need only create and deliver some malware that trivially changes permissions on the appropriate folder. When one considers the potential impact of a future worm or virus containing such a payload, it is clear that Microsoft needs to address this problem urgently.

Eyes and Vision of the New Zealand Torrentfish

Paul Coddington — Sat, 01 Mar 2003 00:00:00 +0100

Meyer-Rochow, V.B.; Coddington, P.E. 2003. "Eyes and vision in the torrentfish, Cheimarrichthys fosteri." In: Fish Adaptations (Val, A.L.; Kapoor, B.G. eds.), Chapter 15, pp. 337-381, Science Publishers: Enfield (USA) and Plymouth (UK).

ISBN 1-57808-249-8

"When water characteristics change, fish have to adjust physiologically to these alterations in their habitat in order to survive as a biological identity. Physiological adaptation is a dynamic and never-ending process that has resulted in myriad fish groups adapting to the vast environmental diversity existing on the Earth. Moreover, adaptively modified organisms acquire greater ability to exploit the full range of natural environment, by adopting new modes of life in many situations. This book is a 'voyage' through Fish Adaptations, including new and not readily available information."

Abstract

Over the last 50 years, much work has been done on the visual ecology, physiology, biochemistry, anatomy, histology and behaviour of fishes. All of these aspects have been studied in detail for a great number of species.

Although it is known that most fish are dependent on vision in many aspects of their lives, very little work of this nature has been done on fishes from New Zealand waters. That which has been done is concerned only with marine species. No information on the visual physiology of any of our native freshwater fishes has been available to date.

This study is intended to bridge the gap, providing information which is complimentary to existing ecological data and acting as a basic foundation on which related, more specialized, projects may build. To this end, the interrelated disciplines of histology, electrophysiology and biochemistry are used to provide as broad a view as possible.

The current state of knowledge concerning torrentfish habitat, life-cycle and feeding habits is reviewed, taking into account the prevailing photic conditions of the waters in which torrentfish are found. Selected aspects of torrentfish biology are discussed in terms of visual function, highlighting those areas where a physiological investigation is essential to a proper understanding of this species. Some informal observations on torrentfish behaviour are included for consideration.

Links

NIWA Atlas of New Zealand Freshwater Fishes