Programs disapearing in xp pro!!!

Hi,
I'm about to go mad! I am on my second XP pro install. In the last, I was installing daemon tools which required a restart. My pc wouldn't restart and I had to do it via the power button, bad, I know. On start-up, the taskbar had disappeared and I had to reboot (again the power button). I slected 'last known configuration that worked. Windows opened and looked fine until I realised that half my programs were apparently missing. I looked in C programs and they were there but could not be accessed through all programs. Some desktop shortcuts had also disappeared as had some window install items such as games.
I decided that I had somehow damaged the reistry and I carried out another new install. This looked perfect and was running well until I installed power iso which required a reboot. It rebooted perfectly but when windows opened......again a lot of programs aren't showing up in START-all programs! Power iso and everything else is in the programs folder but I want to access it the normal way. Also shortcuts for Google earth and Apps have gone.
Some windows apps have gone as well! On the previous install I tried 5 different dates to do a system restore but they all failed. Does anyone know what is going on, please?
Thanks in advance.......

go to My Computer > C: > Documents and Settings > list the folders that you see there

I see an all users folder and my name on the other folder.

Hi, thanks, I've done a complete re-install. Everthings fine but I still have a bit more to install........
Some of the progs were in the two folders but not all.