Hey, I did try that... I changed that string to the latest version available to Symbian... But still get the same error... But my case might be singular cause as i mentioned before this only started happening to me since I used whatsapp on nitroid, and I think the whatsapp servers registered my IMEI attatched to android OS, so now when the same number and IMEI try to register from a different OS client, it probably causes that error.

Edit: Oops!!! Sorry, apparently I didn't change all necessary files, only ui.py... And I changed it to 2.6.97-38***( donr renember the othe numbers) which is the latest version for nokia belle at leadt that what shows on my N8. I'm going to try changing all 3 fikes and then try and register again to see what happens although I doubt it will work cause I've inserted my micro sim in my N8 and registration failed there... So currently my whatsapp only works on nitroid :s... Sigh...
BTW, I used txpad 0.2 to edit ui.py. Just wanted to let everyone know that it works. Just copy the files you want to wdit to mydocs temp folder and maybe keep a backup, then edit the files and copy them over the original ones in terminal with the cp command and path to tje files. (seems a lot simpler with nano... But I dont have it).

cheers