Make sure you've updated your Acrobat 5 to 5.0.5: http://www.adobe.com/support/downloads/detail.jsp?ftpID=1309
You may also want to confirm whether or not this is document specific. Does a new Excel file with just a few letters typed into cell A1 convert fine? If so, you may want to uncheck the 'Enable text and reflow in tagged PDF' option within the PDFMaker preferences. I may have skewed that verbiage slightly as I haven't looked at Acrobat 5 in a VERY long time, but I recall that option sometimes causing Word and Excel conversions to hang.
Thanks very much for taking the time to reply David.
I have updated Acrobat to 5.0.5 as advised but it has made no difference. The problem doesn't seem to be document specific and I have the same problem trying to convert documents in Word too. I can't find the PDFMaker preferences to see the settings. I am using Windows XP.
I get the usual message: 'Now printing on the Acrobat Distiller on Ne03:' then it stops. It's still causing 100% CPU usage when I try to convert.
It may be that you can't use PDF Maker with your OFFICE version (you did not mention the version). If that is the case, you should be able to print to the Acrobat Distiller printer. If that does not work, then try a print-to-file. Assuming that works, open the file in Distiller to create the PDF. My guess is that AcroTray is not working and the steps with the printer will let you know. You may have stopped it.
Thanks for the replies, I have found the solution partly by accident. I searched for others with a similar problem and Googled the AcroTray mentioned by Bill@VT. My PC has been running quite slowly lately and a colleague ran msconfig and stopped the Acrobat Assistant from running at start up. I enabled it again and lo and behold I can convert my files again, albeit slowly sometimes!
Thanks everyone for your help, it is greatly appreciated.