I have checked my computer for worms, viruses, spyware, trojans, etc., and come up clean. Even so, about half of the time that I try to access google.com I get redirected to google.de (in Germany)--even though I and my computer are located in the U.S.! Does anyone know how to fix this problem? Thanks!

Hmmmm...
Can you check your browser language options? Are they set to US-English?
Might be your provider...
In any case, if you would be in Germany, simply clicking "go to google.com" at the botto right will permanently make you stay at Google.com when you enter it next time (until you delete your cookies). If that doesn't work, there might indeed be some malware on your PC...