Cisco Vista VPN Fails if XP VPN installed first..

For some bizarre reason, if one installed the Cisco 4.8 VPN for XP by
mistake, uninstalls it, reboots, and then tries to install the Cisco 4.8 VPN
for Vista, it will fail every time, crashing out with an error with the
msgina.dll or some other library.

Nothing short of a full reinstall of Vista seems to cure this problem.
System restores don't seem to work either. I've seen it do it on Compaqs,
Toshibas, and Dells. It does it on the Business, Home Premium/Basic, and
Enterprise versions.

I would like some way of cleanly removing the old XP Cisco client without
having to go extreme with the System Recovery back to default. Something
like SymNrt like what Norton uses for removal in a Cisco vein would be
stellar.

But any thoughts or ideas would be appreciated.
Thank you.

Gino