1. Stop BlackBerry Administration Service - Application Server
2. Stop BlackBerry Administration Service - Native Code Container
3. Navigate to HKey_Current_User/Software/Research In Motion/BlackBerry Enterprise Server/Administration Service/Key Store
4. Export the KeyStore reg file
5. If there is the CacretKeyStore delete it.
6. Modify the WebKeyStorePass entry so it is blank
7. Modify the WebKeyStorePassIsEncrypted entry to 0
8. Reboot Server
9. Re-run the setup.exe for BES 5.0.2. (This will allow for the WebKeyStorePass to be recreated.)
10. Once BAS-AS.exe reached 300M in Task Manger try to open the administration page.
These are the steps I took and it worked for me. Spent two days trying all types of ways to recreate the webstorepass with no luck. I actually took the first steps from BlackBerry's support page and read a post where the last part worked for someone else on another BlackBerry forum.
Another thing I found out is the Web Administration page does not play well with IE6. Updated to IE8 32bit on my server and page works just fine.
Hope this will help....