I have a feeling my phone might have a rootkit. I downloaded an app from Nokia ovi download application. After that phone is acting weird. If I update the firmware to PR1.2 would that take care of the rootkit or I need to do manual reflash of the firmware?

I don't think Ovi distributes rootkits (and why would anyone go through the hassle of uploading to Ovi, when he/she could just place a link here and have loads of people downloading it within seconds)...

If You haven't upgraded to PR1.2 the app You downloaded might not work as intended, so yes. Try upgrading first...

Maybe the name of the app would help a bit and a better explanation of the problem(s) You're seeing would help us, help You...

I downloaded app called extended call log. After this call logs started to appear weird. saying someone called when they haven't or I called when I didn't make a call.

Has anyone checked with app out.

1) Extended call log is hosted in the Maemo Extras repo, not by Ovi.
2) Extended call log, along with all apps hosted in extras, has been thoroughly tested
3) you dont have a rootkit or any malware, if you're having problems its a bug with the software.
4) Report the exact details on the issue you having with the software here:
https://bugs.maemo.org/enter_bug.cgi...d%20Call%20Log