Laptop freezing and chkdsc running at boot

Thanks in advance for any help!

First, I am familiar with this site, have been helped in the past, and know to go through the "read and run" stuff first. However, I am posting this from my desktop and am having issues with my laptop.

What I am encountering is a random freezing, of random programs (Firefox, IE, other programs, nothing specific) that forces me to manually shutdown with the power button. Trying to get to Task Manager gives me an error.

At reboot, the laptop will run through chkdsc, find and repair a bunch of orphaned files, then start normally.

I have started running through the usual - CCleaner cleaned as normal, SAS ran successfully and found nothing, MB ran successfully and found nothing. I was in the middle of ComboFix when the laptop froze again.

The laptop runs Windows Vista Home. I know that there is probably not much you can do to help without seeing logs, but I can't get them just yet.

Any ideas or tips to continue? Safe mode lets me work normally, without freezing, but does not allow me to install new programs.