If you have Windows 7 this solution may help:
1 Install your CD-key in the registry. This is described in one of EA😕 help-articles. Google on "BF2 invalid CD key". I found out that you must input the CD-key WITHOUT hyphens!
2 Set the BF2.exe file to run in compatibility mode. Select XP SP3 and check "Run as administrator".
Note that you must do all these changes with administrative rights in Windows.
After that you should be able to connect to servers. But you may still be kicked by Punkbuster! So you have to update Punkbuster. Google on "Punkbuster update" and follow instructions you find.
I think all these problems occur because Origin has not adapted the install routine to Windows 7. (Or Windows 8...) The install works in Windows XP.
