about my flash drive after using it for testing it suddenly could not be read by the computer. It can be detected normally and even assigns to a proper letter but when i open it, the computer prompts "please insert a disk in drive F " or something like that...

anyways moving on...
Ive read that 4Mhz oscillators are pretty much unreliable with 9600 baud rate so i might have to change it.. the problem is I cant get any program running in my pic when i change its clock to 20Mhz..is there any other component that needs to be changed?