Problem installing theme on GoDaddy

I’ve googled this a lot, but have failed to find a solution that works.

My problem is when I try to upload a new theme, wordpress freezes on “Unpacking the package”.

My host is godaddy, on IIS. The best solution I’ve found and tried is to change default-constants.php in order for the memory limit to be jacked up to 64MB at all times and recycled the application pool – given I obviously cannot restart IIS itself – and the result remains unchaged.

Thanks for any help.