Can't change metadata, keywords, colors

Question

In Bridge of CS3.  I have tried purging cache, resetting to default workspace, and automatically exporting cache to folder when possible.
The problem cropped up recently.  I was able to add date, location etc to thousands of recent files, but now I am finding files all over that can't be updated thus.  There seems no pattern, I was adding colors to a lot in a folder and then many would not accept it.  The same files would accept a rating.  I couldn't change the description on a whole batch that was misnamed, nor could I delete the old one.
some other strange behavior.  All added metadata disappeared from some.  And on some RAW files with added dates,that is lost in a created tiff.
Some tiffs have the modified date instead of the original created date in the info under the thumbnail, which is set for file name, created date and size.
I have gone to folder properties and changed from read only if set. but it doesn't affect all files in a folder
the message is "There was an error writin metadata to [file name here]"
Sometimes the RAW file is unchangeable but its tiff is, other times neither.
This is all from the IPTC core.  If I go into file info in Photoshop I can change, I just discovered.

Answer 1

As with almost all my problems, there is apparently no solution, so I am going to try reinstalling photoshop. So can someone at least tell me what is likely to be overwritten so that I can protect it.  And where they are stored? EG Web Gallery templates?  Keywords?