What computer operating system is your Premiere Elements 8 running on? For now, I will assume Windows 7, 8, or 8.1 64 bit.
First, the usual drill for the Premiere Elements 8 users...
a. Are you working from the 8.0.1 Update of the program? If so, please download and install.
You can do this download and install with the program closed.
b. As soon as you can get into an opened project, make sure that you disable the automatic Background
Rendering and AutoAnalzyer features. Background Rendering in Premiere Elements workspace Edit Menu/Preferences/
General and AutoAnalzyer in Elements Organizer workspace Edit Menu/Preferences/AutoAnalzyer Options.
c. Do you have the latest version of QuickTime installed on your computer with Premiere Elements?
d. Are you running the program with administrative privileges?
e. Does the problem exist with and without the antivirus and firewall(s) disabled?
f. Is you video card/graphics card up to date according to the web site of the manufacturer of the card?
When you did your uninstall/reinstall, how did you do that?
a. uninstall the usual control panel route
b. free ccleaner run through to get rid of leftovers from incomplete uninstalls reinstalls
c. reinstall with antivirus and firewall(s) disabled?
If possible, please post a screenshot at what you are faced with and cannot go further with.
We will be watching for your follow up and then we can decide what next based on your reply.