Please be more precise.
I see three major steps in your description -
1- import from Oracle
2- query generation
3- export to excel
At what stage of each of these steps does it lock up?
Have you verified each of the prior steps are complete?
How are you doing the process? Manually or code?
Is it an automated process or one interactive (clicking buttons on a form?)?
My personal guess is, based on how you wrote this out, is that the first two processes are working and it's failing with the export to excel.
Based on that premise, I would ask whether the process has ever worked? Does it, perhaps, work once and then all future attempts fail?
If yes - it is highly likely that you are not closing the excel object properly. Doing a quick control-alt-delete should show you one or more excel.exe processes still running - and, if so, manually killing them with End_Process should allow it to work one more time.
Assuming the above is a good guess, try these links which may refer to other posts.
http://www.mrexcel.com/board2/viewtopic.php?t=147132&highlight=usercontrol
http://www.mrexcel.com/board2/viewtopic.php?t=102394&highlight=usercontrol
Mike