Something (was) wrong with tunnel.sys

I've had a rather tricky problem recently. Three times this week, my Vista Home Premium install has gone wrong. Every time it has just stopped half way through booting, and done nothing more. Each time I have simply popped the install DVD in the drive and used the system restore on the disc to sort it out.

While checking if Safe Mode made any difference (it didn't), I found out that Vista loads crcdisk.sys and then stops. Consulting my (old) boot log, I think I can be pretty certain that the driver after this one is tunnel.sys.

The problem flared up when my computer simply wouldn't boot the Windows DVD - the BIOS did it's job fine and the message "Windows is loading files..." came up with the white bar, but after that it just returned me to the useless hard drive boot screen.

To sort this problem out, I have had to remove the hard drive from my computer and put it in an external caddy, plug it into an old computer (via USB), boot the Vista DVD on that machine, and do a system restore from there. I also used the hard drive checker (in the Tools tab of the properties dialog for the disk - it showed up as an external hard drive) and the other tools on the drive for good measure, and returned it to my computer.

I am currently typing this into Firefox on the Vista machine, so everything is working fine *right now*. However, all my system restored points have disappeared, which is odd.

When I contacted my computer's manufacturer (Eclipse Computers), they told me to format the drive and start again - fat chance!! - and warned that it might be a virus/other malware. Mainly for peace of mind, I have installed the full Kaspersky Internet Security 2009 suite, and will buy it once the trial ends. I think that