Access database slowdown

My company is using an Access database to keep track of donors and donations. Within the past couple of weeks, the database has become incredibly slow (around 10 minutes) when switching from one form to another. It appears to have started after it was opened (but no design changes made) in a computer running Windows 2000 and Office XP. Most of our systems are Windows NT and Office 2000. I have run a detect and repair on the database, but it did not correct the problem at all.