>SQL Server 2K MSDE has been running fine on this machine for a couple of years.
>I tried to add a 10 byte index to a 1.2 MM record table (200 bytes per record) and got "out of space on file group primary. To correct, add space"
>Never had this before.
>The DB's properties call for autmatically expanding the space.
>The DB is all corrupted now.
>Is there some kind of limit in MSDE or is this some kind of fluke?


Asking the obvious question, is there still space on the drive? If not that, check whether the database has a max size that has been hit.

Yes, MSDE has a limit. It is 2 GB per database.