Can you give us a bit more to go on than just the one sentence?

What version of Timeslips?

Where are you trying to display a previous bill? From the topmost menu? Within Billing Assistant?

What is the sequence of clicks before the "freeze?"

When you say your computer "freezes." do you mean that you cannot do anything else in any other program and have to reboot? Or is it just Timeslips that does not respond? 

Nancy Duhon, Esq.
Duhon Technology Solutions, LLC
Master Certified Consultant for Sage Timeslips
Providing individual Consultations and Third Party Remote Desktop Support - including older/unsupported versions.
404-325-9779
[email protected]

More than likely that is easily correctable using the Knowledgebase article 43161. 

Go to SageKB.com and enter that number.