ITunes Store Connection Problem and R6025 Error

Question

I have a problem with iTunes (v 7.6.2.9) on my desktop machine that I haven't been able to resolve. The same version works without problem on my laptop, both are fully up-to-date XP SP3 installs with no iTunes add-ons.
iTunes starts correctly, but then does one of three things:
1) It hangs during connection to the Store, with the bargraph almost at the end of the travel.
2) It brings up the Store page, but although I can move the cursor around to click the Store links, nothing happens. Eventually the 'Accessing iTunes Store' bargraph may appear but it never connects.
In both of these two instance, no error messages appear, the Store simply locks up. I can still use iTunes perfectly as a player, access my library etc. However, I have to CTRL-ALT-DEL to close the iTunes process from the Task Manager.
3) As per (2), but about five seconds after the Store appears, an error box pops up:
Microsoft Visual C++ Runtime Library
Runtime Error!
Programe: C:\Programe Files\iTunes\iTunes.exe
R6025 Pure Virtual Function Call
Pressing OK closes iTunes.
I've done all the obvious things - removed and reinstalled, cleaned out registry errors using jv16 Powertools 2008, I've even used Process Explorer to examine all the dlls in use with iTunes and compared the version numbers to the correctly working version on the laptop - they're all the same. I've also run a low-level memory error checker, but it passed with flying colours.
So I'm a bit stumped to know how to take this any further. I know other people have had R6025 problems in the past, but they seem to have generally been resolved by installing a later version of the application... which isn't much use to me, as I'm on the latest already. Incidentally, I did try going back one version to 7.6.1, but that behaved in exactly the same way.
If anyone has any ideas about how to troubleshoot this sort of problem, I'd be very interested. I'm assuming that I have another application conflicting with iTunes, but I've no idea how to find it.
Thanks,
Steve

Answer 1

Yay! I've found the culprit...
For historical reasons, I still maintain my old Compuserve 3 account as my public e-mail address. Part of the CS3 installation is a Remote Password Authentication system called Virtual Key. I noticed that these dlls were being invoked during Store connection attempts, which I thought was a little odd.
I deleted the following files from Windows/System32: (annotations courtesy of the Compuserve info text file for Virtual Key)
RPA.DLL - The dynamic link library that implements the RPA protocol for Virtual Key.
RPACFG.DLL - The dynamic link library that implements the Virtual Key accounts wizard API and other configuration APIs.
RPAWINET.DLL - The dynamic link library that is required to enable Virtual Key for Internet Explorer, version 3.0.
RPASSPC.DLL - The dynamic link library that is required to enable Virtual Key for the Internet Mail client and other non-web clients.
RPAEDIT.EXE - An editor application for editing Virtual key Accounts as well as viewing and deleting sites from the Virtual Key Site List that is created by Virtual Key when accessing secure sites.
RPAUI.HLP - Help for Virtual Key features.
VKUNINST.DLL - An uninstaller program for Virtual Key.
RPAINFO.TXT - This file.
As I only access Compuserve through the proprietary CS3 front end, removing Virtual Key has had no impact on my Compuserve mail system and iTunes is now working perfectly.
I hope this information might be of some use to others in the future!
Steve