Printfil shows "File not found or corrupted - Error 0" before my DOS job gets printed or previewed
It usually happens when Printfil is setup to capture a parallel port, because Printfil tries to manage the captured source print job too early, while the source program (usually DOS) is still locking it (the source print job isn't yet finished, or at least, Windows thinks so).
With Printfil 5.5 or newer you might see this error message coming up even more frequently than before, because it's much faster than previous Printfil versions when capturing an LPT port.
You might solve it simply by increasing the Printfil's Timer in Configuration -> Standard, so that Printfil checks less frequently for something to print. The overall process respect previous Printfil versions will not slow down because, as I said above, the capturing process is faster.
However, if you've to setup the Timer to a too high value to solve the problem, then your own source program is not closing the LPT port at the print job end, or it's hogging the CPU. If so, you can find other solutions than increasing the Printfil's Timer in the article: How to make DOS programs printing faster in Windows