System Restore failure - yet another tale of woe!!

OK, I've seen loads of posts by people who have lost their system restore and I have tried all suggestions but still have the following problem: I can create a System Restore point OK but when I try and roll back to a previous point, it goes through the motions and when the desktop screen reappears I get the message that System Restore failed. I also checked someone's suggestion and traced a report of error message 8206.

So far I have tried,
SAFE MODE REBOOT and then trying it - no good,
DISABLE/ENABLE - no good
FIDDLING WITH VOLUME SHADOW SETTING - no good.

So, what is there left to do??? I'm at my wits end. I did create a system image a few weeks ago but, for all I know, the System Restore problem might have been there when I did it.

I do NOT have any installation disks as I bought the PC off someone with W7 already installed. All I have is a System Repair disk that I created early on (maybe the problem was not there when I created the disk months ago). Is there any way I can rebuild the registry settings even though I don't have installation disks??

On a slightly different point, am I too late now to do a disk partition??. Windows was already loaded on my PC and I added all my programs & files. However, they are on the one c: drive. Ideally I would like a separate partition for the OS but I fear it's too late as it's all mixed in together and I wouldn't be able to separate out the OS from all the other things. Is this correct??

Thanks in advance for any advice or suggestions, especially about Sytem Restore as I think I've tried everything!

I'm not sure if this is relevant or even if the error message is the same but AV products can interfere with SR. Make sure you switch of any anti tamper that they may have before doing the SR.