I've had that problem as well, although not as frequently as you. The issue I have very often with IE7 is that it becomes unresponsive when I try to exit out of it. I have to go into task manager and terminate the process.
I've been using IE7 for some months now and have yet to have a problem with it.
What kind of add-ons are you using? If they are not IE7 compatible, they could be causing problems.
Open the Tools menu and selsct Manage Add-Ons. That will open a dialog that shows all add-ons. You can choose from those currently in use, those that have ever been used or those that run without permission.
Start with add-ons currently in use. Make a list of the add-ons then disable everything. See if that corrects your problem. If it does, you can re-enable add-ons one-at-a-time until you start having issues again. Make a note of what you enable as you do it. Then disable the last add-on that you enabled to see it the issues go away. If so, you've found the problem...if not, disable the previous add-on in the list.