It sounds like you have resolved your bad checksum problem. However, the bad checksum indicates some internal corruption, which may or may not be causing your static.
I would try a CLEAR SETUP (hold down SETUP key on startup at second start screen. If this does not do it, try a "Clear internal programs and setup" (UM p.79). If this does not do it, check all your cables and connections very carefully. If this fails it will need to beck looked at: email@example.com.