Unexpected system restore

I left my computer running (Vista Ultimate 32bit) yesterday afternoon, and when I came back to it the next afternoon there was a message on the screen that I had successfully restored the system back to a checkpoint four days ago. I did not initiate this system restore, and I'm trying to figure out where I can find any log files that might tell me why it occurred. I've done a lot of work in the last four days, and having the Registry rolled back worries me because it might wipe out useful settings and changes that occurred during that time period. I'd appreciate any help understanding the conditions under which Vista will elect to restore itself without my intervention, and where to find any logs or records.

dont really know why this has happend mate all i can say is doe it will not delate any important files or anything like that as it system restore it just goes back to factory setting as you brought it ((any programmes you put on ect will be gone)) but it go back to it normal self as you 1st brought it soo dont worry there but as for rest thats werid how thats done itselfff (maybe some were on net someone alse sufferd this or on here n have soultion mate )