have you tried running from a commandline and passing the param's? at least you can determine exaclty what is being outputted without leaning on the error logs.

./scriptname name=value talk=another value
[download]

since you are opening the TAG file for write, could very well be a permissions issue. of course, running commandline locally won't debug that issue.

I don't see a header written in errorHTML or prior to it's potential invocation, you might want to place a header call or the equivilent Content-type line(s) to force the message to the browser.

keep in mind it's 11pm and I have been partaking in some wonderful wine tonite...so some sort of disclaimer is more than appropriate :-)