i have also the same problem recently.
My pc drives D,E,F,G wont open while I double click on them, Also now it creates a great problem like, when i double click on them it opens the Open with menu for choosing a programme to open. I have tried with my best to solve the problem but i cant. I have reinstalled my windows xp but although C drive can be open by double clicking but not the others. I checked my PC for viruses and cleaned. But it not works at all. I could not understand the problem please help me. With a solution please send me a mail to me sin.rohit@gmail.com .