more than likely, if you bought it from cricket, they've disabled dial-up networking. the easiest way to tether on cricket is with an non-cricket android phone. if it's a non cricket m540, just look around and more the likely to find the answer
.dll =Dynamic Link Library used by the computer and is not loaded into the phone. Depending on what solution used to flash the XV9900 and what PST used it is possible the setting could revert. "Especially after a OTASP"
Use the correct .dll for starters, that may cure your problem.