mac entourage problem ... why is my database not rebuilding?

i need to switch my identity to a different computer (im at work -both using entourage x) ... tried switching then an error comes up -

ENTOURAGE CANNOT ACCESS YOUR DATA. TO ATTEMPT TO FIX THE PROBLEM REBUILD YOUR DATABASE -

i try this but this then come up with ....

typical rebuild - COMPACTING FAILED THE END OF FILE WAS REACHED -

i then try advanced and this comes up - REBUILDING FAILED THE END OF FILE WAS REACHED

.... it then come up with the message .. REBUILDING FAILED IT IS LIKELY THAT YOUR DATABASE CANNOT BE REPAIRED ....

i then try to reinstate the database on the original computer and it works fine... i have made sure that all files are not read only and ive tried making a archive.....

nothing works.... HELP