In this scenario, if CHKDSK found and fixed Errors, I would run it at least twice more.
By "at least", I mean that CHKDSK should be run at least once after the prior run finds no errors.
I do realize you are having trouble booting, but you appear to be able to boot "occasionally".
If my dense brain is serving me at least minimally, I recall that you've installed and uninstalled quite a few applications and/or utilities recently?
The HD File Structure (which CHKDSK works on) sometimes gets a bit scrambled with multiple install and uninstalls.
You mentioned FIXBOOT in a much earlier post.
Do you have a "recovery partition" on this machine?
If so you can run FIXBoot from Recovery Console.
Here's some instructions from MS:http://support.microsoft.com/kb/314503
Please note that if you have a virus infection, using FIXBOOT may have "undesireable" results.
If at all possible, download and run HiJackThis, and post in our Malware Forum.
I'll watch your progress there.
When you are all clear, we can resume this work.
If I am totally missing the point here, I'll see if I can get a knowledgeable Tech to look in on this thread.
Please let me know.