When there is a hang, it is usually one of two things - Toad is either using all your CPU, trying to get something done, or waiting on Oracle to finish a query.
If the former, you should be able to see that in task manager on the “performance” tab. It will be easiest to see if task manager shows one graph per CPU. (View -> CPU History -> One Graph per CPU).
If the latter, CPU usage will be zero (at least due to Toad) and if you look in the database (using another Toad or sql*plus, you’ll find that in the Session Browser or in v$session, the query belonging to the “hung” copy of Toad will have session stuck on “ACTIVE”. If this is the case, go to the “Current Statement” tab and tell us what the query is. Maybe we can rewrite it.
The info above + a description of what you were doing in Toad is enough to get us started at least.