Long running vb/a code Issues

Hi All,

I need some advice to getting excel, a user form and vb/a to play nice with each other and the os.

I have a user form w/ vb code that can run for a minute to an hour depending on what parameters the user selects.

When the code is running and excel minimized, it can't be restored until the code completes.
additionally,
if I select the form and try to move it there is a few minute delay before it happens
if a application is opened over the user form or excel, then closed, the user form and excel image is blanked and doesn't repaint for several minutes.
on occasion, when I open task manager, I see excel and MS VB for Appl. in a non responding state
There isnm't any issues displayed in task mngr, the machine is running at about 45% cpu utilization.
However, other apps, appear slow to respond at times when the vb code is running.

I've sprinkled do events and repaint through out the code modules but it's a poor attempt at best.

Also the code appears to sporadically hang, if I hit a ctrl+Break, then resume, the code continues
however, at the break point, I add another DoEvents

Is there something I've over looked?

thanks