I found a solution to this problem without removing the Venturi application:

http://forums.ceruleanstudios.com/showthread.php?threadid=56383:

Old 22 May 2004, 07:42 AM
There is a known issue with Venturi Wireless (the source of VLSP.DLL) and Trillian. Basically, removing the “transparency” option from Venturi solves the problem.

It can be done from Add/Remove Programs without uninstalling Venturi entirely, or it can be done by double clicking on C:\Program Files\Venturi2\SPI\Uninstall Transparency, which is just a link to “C:\Program Files\Venturi2\SPI\inst_vlsp.exe /u”.

I did this and now I don’t get crashes from vlsp.dll (which were occurring also for other applications besides avast).