You might want to take a look at this node. I suspect that when you try to run a shell command (via backtics or system) that the process that Perl spawns is butting heads with another process already running in the background. In my case (the node referenced above), it was Norton Antivirus.

I eventually ran it down by killing unnecessary tasks running in the background and re-running my Perl program. You didn't say what Windows OS you were running, but even if it isn't Win 98, I would still check for this type problem by eliminating unnecessary background applications. I switched antivirus applications and my problem hasn't recurred (I'm using Command Software Antivirus).

--Jim