Access Closes Unexpectantly

I have been designing a database for a few months now and not had any 
problems, however this week when i am using the database access keeps 
cra****ng.  I have run the database on a different machine and it works
fine 
and i have also repaired my office installation and i am still having 
problems.  The problem seems to occure when i try to move records or use
any 
button on any of the forms.  I have tried working in debug mode to see if
it 
is a particular line of code which is causing this however in debug mode
the 
system does not crash.

Any ideas?

John Speed