Vista - Help Please - Multiple issues

I have a Toshiba Satellite 600 running Vista home Premium (32bit)... I had a load of problems with adware... I looked on some other forums and the general idea I got was to install a registry cleaner to stop the problem... I installed CCleaner and ran the standard cleanup... this had no effect at all, but now the adware is the least of my problems...
I'm not sure if its the Reg. Cleaner that did it, my laptop used to freeze from time to time but now I'll be lucky if I can go half an hr without it locking up. It seeems to be mostly when I am connected to the Internet, Bittorrent and Explorer are the main culprits but also when I have WiFi disabled and when running Media player. The bigger problem I get is that when I ctrl+alt+del it either has no effect or I get a blackscreen with a box saying "error failure to display security option" (or something similar) but no error number... (I am running explorer with add-ons disabled to write this, seems ok for now).
I also have updates available (3.5 .NET framework) which refuses to install without locking up with no signs of life for hours, despite other updates installing fine.

I have tried a number of solutions:

I have tried umpteen times to install updates, auto and manual, always with the same result..

I have done a System Restore (to the oldest possible point, 10 days i think before the Registry Clean) with no effect but to have a few programs i recently unistalled back...

I have tried to re-install windows but when I use the recovery disc I got with my laptop (which says on it the operating system and my laptop model, not to be sold seperatly) the disc says its not compatable with the version on windows installed on the hard drive...

I also discovered I'm not the only one to have these problems with the 'failure to display security options' dialogue... the only remedy that people said had worked (that I found) was a series of command prompts in Dos, as an administrator. I tried this several times but once I reach: REGSVR32 WUPS.DLL my laptop promptly freezes.. (heres the link to this chain of commands Failure Security Options - TechSpot OpenBoards )

I am not sure if it is coincidence that this trouble has come after cleaning my registry as I have had a few more freezes than usual lately, but I am travelling and so need my laptop to be in working condition.

Surely there is something I can do short of formatting my hard drive?

Please help...

PS: my laptop has two hard drives... if i format C: drive (the one with windows) will I lose all data on D:? In other words can I back up my C: documents on my D:?

Ok
First a registry cleaner doesnt stop malware, and in fact can lead to Windows corruption.
note- if no restore point exists to fix problem re-install may be your only feasable option if a repair cannot be performed.

Install a good antivirus/antimalware program, use Windows defender, and always use UAC.

Copy/backup your User folder under "computer", and then re-install by placing O/S disk in drive, restart hit any key at prompt and follow install prompts. at screen where it asks where you want to install; delete/format C: partition (Windows is currently on), and then install Vista.It is not recommended to backup documents/data on the D: drive if this is a recovery partition. You can though, delete/format this partition and then use it as a data drive if you so desire.

I recomend Avira or Eset's NOD32
Try this:Free ESET Online Antivirus Scanner

sure thing ill give it a shot... thanks very much for your help, i'll let you know how it goes

Cheers