I've run the SP1 install on all of my family computers. I also had some slight problems until I updated all of the associated drivers, dlls Etc.. Once the updates were complete (About 15-20 minutes download time on a cable modem!!) I had to reboot twice for the settings and registry changes to sort themselves out. Once all was said and done it runs better than before, stronger, faster. And tha is in five seperate cases 2 Generic desktops, 1 other desk top and 2 laptops. Symptoms and cure all the same, complete update not just SP1.
Hope this helps. :)