What do you mean by "my hard drive C: file" ? What is it ? If it is a file (usually named HF:Hardfile0), then check if the HF: assign still points to the same directory and that there is a file called Hardfile0 in it. Shouldn't be too difficult.
If "my hard drive C: file" is a partition dedicated to PC-Task, check if the partition is still there with the same name and dimensions (should be listed in the output of the Info command. Otherwise use HDToolbox to check).
Neither MSH nor the FastATA can interfere with the work of PC-Task. BTW, you should use Fat95 instead of MSH because it supports long file names. Fat95 is included in the Poseidon archive and you only need to copy it to the L: directory, then Poseidon automatically uses it to mount removable USB drives.
Bye,
Thomas
