Sure but not to of the same ones..
Site Errors?

Well keep IE 8 becuase you need that to get automatic-updates from microsoft that are important for your computer. (But don't use it)
Use Chrome as your main-browser if you prefer it. (Is quite a lot faster than IE 8 anyway.)
Additionally you need to choose which to make ''default-browser''. I would set Chrome as this also.

when i play chess against someone rated 1500 or more, i lose. i'm not sure what's wrong with the site but it's really annoying.

When i go to home/online chess, to look at all my games on the tiny boards the boards are kind of messed up and the pieces are a little cattywumpus. ?

This damn Google Chrome is still screwing up just like it was. I thought it was supposed to be an improvement.

i can't open any contests at any of my groups , when i open any of my group forum & i click to any subject or contests to read it , it doesn't work at all , i tried through the firefox , google chrome but i couldn't !
i'm completely isolated & i can't receive my rights as a premium member here.
i need a solution to this problem which also i cannot send this problem through the help & support site help !!!
Can you have two browsers at once, and use one sometimes, and the other the rest of the time, without things messing up?