What could cause Windows Indexing to suddenly dump all its memory?

Factual Questions
1

Hello, here is my situation. This morning when I got to work I tried to pull up a file I needed by hitting the Start Button and typing the filename, which is how I always do it. Didn’t work. It wasn’t a big problem because I am very careful to save files in the appropriate folders so I was able to tunnel down from the Documents folder and get what I needed in only a few clicks. But I was still concerned so I tried another search and all the Start Button would bring up were programs. Windows Search would not find anything at all. So I went over into the Administrator user so I could force the Index to reform itself. Search is working fine now.

Anyway here is my question. What could cause the Index to just collapse like that? I am running Windows Vista if it matters and I have AVG and Adaware on the computer. I update the virus definitions everyday and run each one every day and I run CCleaner about once a week to clear out the temp files. No viruses were found yesterday. Will run AVG and AdAware again tonight.

Can anybody help? Thanks very much if you can. If not no problem because I am just curious.

2

I found when I defragment the section of Windows that stores the Index, oftentimes I have to rebuild it

3

Is that like defragmenting the hard drive? If so I had not done so recently; I do that on the first Sunday of the month.

4

actually IIRC vista has a default weekly scheduled task to do it on its own, but I havent had my coffee yet…kinda fuzzy still

5

I think I disabled that in favor of checking myself. But are you saying that Windows could have destroyed the index itself? Why would they let it do that?