2
What you need to do, is give us some debug information. With this information we can analyse the problem and create for you a solution.
Go to system admin -> preferences -> general settings. Halfway down the page there is a debug setting. Turn that on PHP debug.
Then, try to upload an image again. Ignore all the notices and warnings you may be getting. This is about finding the cause of the blank page. When you get to the blank page, copy the fatal errors that produce the blank page to this thread.
Then we can see what is causing this error, and we may be able to provide a solution to your problem
Herko