When I add the following to my CSS:

table {
border-collapse:collapse
}

Prince exits with this error:

techsupp:~> /usr/local/lib/prince/bin/prince -v sys2.html -s /tlm/www/css/default.css
prince: Loading document...
prince: loading HTML input: sys2.html
prince: loading style sheet: /tlm/www/css/default.css
prince: loading style sheet: sys_files/default.css
prince: sys_files/default.css: warning: can't open input file: No such file or directory
prince: Converting document...
prince: warning: no glyphs for character U+004C, fallback to '?'
prince: internal error: no fallback glyph for character U+004C

If I comment out the table lines, it runs perfectly.

Any idea?

Well, I've solved the problem by specifying the class instead of applying it to "table" as a whole:

.tlmtabledata {
border-collapse:collapse;
}

<table class="tlmtabledata">

That works fine. I still think the other way should work...

That error message means that there are no fonts available, and has nothing to do with collapsing table borders!