One problem was caused by the back up process.
A had grown so big that the views coul dnot be re-indexed.
I deleted the file cafcr.db and this sorted out the problem.
Smaller databases with small view indexes were ok.
Compacting the databases or deleting some old ones also helped free up space/resources.
Another solution was to change the windows environment variable on the server to point to more space for temporarily
storing view index files. ie from c:\winnt\temp to d:\temp