Commercial use of font with GPL licence

[Lars]

Hello,

in IRC I got the hint to ask my questions here. Sorry for my english.

I published a true type font under GPL license. You can find it at 
http://fixedsys.moviecorner.de

Today I got an email saying (free translation):
 > "we want to use your font (f.e. because of the euro sign)
 > in our pps system. Because of the GPL this is not allowed
 > for us without payment."
I don't understand what his problem is and I don't see problems with 
using the font in their system if they give a text file with the GPL 
license with it and install the font on the customer's system.

May this company take the font and give it away to customers if the GPL 
is included and software itself makes use of the font via the OS? The 
font is not included in the software then, it is not linked. It's just 
installed as the customer would have downloaded it from my website.

Thanks in advance for your answers,
Lars Naber