Cannot install or run applications on Windows 7

I am running Windows 7 64 bit with 8 GB of RAM on a Asus/Nvidia 780i motherboard. The OS is installed on a 30 GB SSD OCZ hard drive.
Pretty happy with the speed, and responsive of the system. I install most applications on a TB drive assigned as H. However, sometimes I have problems starting the PC from cold boot. It hangs at a blinking cursor (right before loading the boot menu) and sometimes it just shows lots of colors (garbage) on the screen. I did not have problem running Vista on the same machine for a whole year (until I killed it by shutting the PC down while it was on sleep mode)
Anyhow, I also think that maybe the system is shutting down too fast.
I had problems with steam, which would not even open (it will open for a second). I had to uninstall and install again. I have the same problem with Bioshock. I have not tried to re-install, because it works fine if I run it from the install from my Vista drive.
But the software that annoy me the worst is AnyDVD. I had the trial (and I was seriously thinking on buying it) but it won't uninstall, and it won't run. If I run the installation that was installed on Vista it runs but it tells me that there is no drives available (the drive letter assignment is different in Vista than on 7).
So, before I try re-installing 7 again. do you guys have any suggestion on what I can do to fix it, and what might have caused this problems?
As i put in another post my Vista does not have network and that is why I installed 7. I have XP/Vista and 7, all in the same machine but in different physical drives

Hijack this!
Spybot S & D
sfc /scannow
a bigger hard drive
various tools from sysinternals

Hijack This and SB I don't think will help, since I am leaning towards a corrupted OS (since it frezzes sometimes at boot, before the OS choice screen), but I do like the idea of sfc /scannow so I will try it.
The drive for the OS still has 10 GB free, which is pretty good for 7, and getting a bigger one is actually out of question since they cost so much still

I tried sfc /scannow but it did not find any integrity problem.
However, when I came to the forum I also noticed that the forum did not showed me as logged is, even thought I was logged in (and logged in twice to make sure)
I am wondering if at any time I messed something up with the profiles, or the permissions.
My profile runs from a different drive than the OS so I don't run out of space.

I think it would take less time doing a repair install then trying to google and find a solution.

Windows 7 does not have a repair install it seems. I tried both at home and at work. Every time I chose repair it tries to give me the repair command or just regular install. Damm, I suddenly miss XP so much :P
So, another machine at work is also not working right. I think I have narrowed the problem to the SSD drive. The SSD drive at home and work are different. I am wondering if there is a problem with the motherboard support (even though both are different as well).
Currently I cannot even delete the partitions from the SSD at work so I can start from scratch, and the Windows 7 boot takes ages.
At home however, I did also find a couple of viruses, but they weren't running, so I am not sure if that was the problem.

UPDATE::
I think I solved the problem with my home PC (where I am writting this post now)
I had w32:sality worm, which injects into the beginning of the exe files. and guess what, all the software I could not run was infected.
I am very careful, but if you want to know how I got it it is simple and dumb.....
USB drive that I used to clean a customer machine. OK, before you go all out and think I was very dumb...the USB drive was formated before, and I use it now as a READYBOOST drive. Somehow it stayed in the autorun.
Most of the software infected was new software that I had installed in the past 2 months, so re-installing is fixing most of the problems. Except for some software that I had on my partition for XP, which I don't have copy, like Age of Empires Gold and Star War Knight of the Old Republic. So I guess after all the damage was not too bad.
BTW, I removed the virus using avast free version 5. I really like the new interface

Wow Dehc... that sality seems troublesome... a few clients keep getting this virus, so I'll keep my pe... personal usb out of their systems me thinks ;)

Avast 5?! Rev, where's the news link?! I'll download asap.

dehc, Is your usb now clean?