other concurrent activities have reused the available space.

HI,
I have a UK customer who's working with Attain 3.70
Everything works fine, but once in a while when a user wants to log on
Navision gives the messagage:

Other concurrent activities have reused the available space in the database that contained your snapshot of data.
This can occur in connection with time-consuming tasks such....

(well if you know the message, you will know the rest)

The advice you get is
- expanding the database
- deleting data
- date compressing
- optimize

However, the database is not big and there is more then enough space available. Also the cache is big enough.

Anybody else had this problem before?

thanks for any help.