[Joan Solsona]"Is it possible to downgrade without having to format my hard drives? "
Sure if you want to have even more problems then you are having now. When you move to a new version of an OS all the settings that you have update also, and those now updated settings will not play nice with an old version of the OS.
You can try reinstalling the OS, and but I personally would just reformat and install clean.
You should however at least boot from the install disk and run disk utility, or if you have disk warrior run that.
thanks zane, i just formatted the hard drive and reinstalled most of the software, it was easier and quicker than i thought it would be.
I'm working now on 10.6.2 and everything seems working just fine, fingers crossed.