Invalid Jar file - on ANY download from OVI store ...

OK, so I'm trying to download a few freebie games (Yetisports/Penguin thingy 2 etc etc)
Whichever download I choose on my phone, and I get to the installer, it tells me that the Jar file is invalid. **bleep**!? How do I sort this before I pull my hair out?
Phone in question is the E72-1
This is a joke from Nokia, forcing you to download their OVI files through your phone.

ok, i am using a nokia e5 and this are the problems i am encountering:
1. I cant install jad files anymore, it just says disconnected n i hav used different sims.
2. My phones freezes and restarts.
3. Most application i open just exits on its own.
4. Invalid jar. Files.
5. I dont know the best antivirus to use for my phone. I dont think netqin is gud cos despite i installed it, i still had virus.
So pls help me out in accordance to the above listed issues i m havin.