I purchased a boxed copy of Parallels Desktop 3.0 from Best Buy. I installed the software, but when I typed in the serial number from the CD sleeve, I received an error message that my activation key is invalid. (By the way, my activation key has no "?" in it.) I attempted to return the software to Best Buy, but they refused to accept a return of opened software, even if it is defective. I've sent an email to Parallels Desktop support, but does anyone know what the problem might be? To say the least, it's very frustrating to pay $80 for defective software. From what I've seen based on the posts on this forum, activation key issues are very common with this product. This company really needs to wake up and deal with these activation key issues or it will get such a terrible reputation that no one will buy the software. I certainly would not recommend it to anyone.
Any I's, L's, or 1's in it? Looking at my activation keys all the letters are capitalized, so if it looks like | then it is either I or 1, not L. Also the code should be 5 sets of 5 numbers/letters, separated by dashes, like ABC12-DNV34-5GHI6-J7KL6-M3NOP (just an example of what it should look like, not a real activation key) so make sure that your key is the right length and in the right format.
brkirch's suggestion worked, so I finally was able to enter the activation key. What appeared as "l" on the serial number was actually the letter "I" and not the number "1", so what I read as "15Q4U" was actually "I5Q4U". They really should use a more legible font for their serial numbers. Thanks very much for all of the replies and the help.