I get a timeout message at the end of a print run

This is an issue between the file you're trying to print and the printer not being able to read it correctly.
Try copying it and pasting it in a new document (preferrably different program) If that doesn't work, try to install and use another driver

It is a timeout value which works only when a job
with a specified size is received.

A Google search netted this proposed solution:

I would reset the printing system from within System Preferences. Then, set up the printer again.
http://support.apple.com/en-us/HT201539

Check the printer's memory modules for a good contact with the slot . Take them in and out a few times to shine the contacts.

This is a corrupted Postscript error.
Possible solutions are, reload up to date driver and/or firmware. Go to Xerox website address below for drivers and firmware.
http://www.support.xerox.com/support/phaser-4500/downloads/engb.html?operatingSystem=winxp&fileLanguage=en_GB
This could also be a program specific problem, try printing from another software package.
Finally, you could try an NVRAM reset. Go to 'Troubleshooting', 'Service Tools', 'Reset NVRAM'. WARNING, before performing an NVRAM reset, print out a configuration page. 'Information', 'Information Pages', 'Configuration Page'. This print out will give you all the printers settings, including your network settings, which will be lost through the reset. You will need to re input them through 'Printer Setup', 'Connection Setup', 'TCPIP'.
Hope this helps.

When I went to My Page on your site, running along the lefthand side were problems similar to mine and how they had been solved. I used the suggestion of looking for a "hidden" paper jam in the back of my printer and that indeed was the problem. Very grateful for such a quick and easy solution! Thanks.

It is a postscript error, refer to here
http://office.support.xerox.com/SRVS/cgi-bin/webcgi.cgi?new,kb=Phaser_6250,company={5AC8CA72-62D5-4658-8D6F-D2F393C98A63},ts=xo,ques=ref%28security_level%29:1,ques=ref%28Country%29:45,/,case=R1002035441

I am having the same problem. Sometimes my Xerox Phaser 8500 prints a PDF or web page fine, and other times I get pages and pages of what looks like PostScript code. I thought I had installed the most recent printer drivers, We are using primarily Macs with OS 10.4 or 10.5. One recent change is that we connected the printer to an Airport Express using a USB cable, which is sweet when it works correctly....any ideas???

This is from Xante's 3G Manual (downloadable via PDF)
"Printer Timeout The Timeout feature allows you to select the number of seconds the
printer waits for additional data before cancelling a job and returning
to the READY/IDLE state.
Set Timeout from the MISC:TIMEOUT configuration menu. The
factory default of 40 seconds (40 Sec) is an average setting. Set
timeout according to the type of files you send. Use a low setting for
small, simple files to prevent an indefinite tie-up on one job. Use the
300 or Never setting for large files, such as graphic intensive or CAD
(Computer Aided Design) files, to allow enough processing time.
With the NEVER selection, the printer does not timeout; it waits
until it receives additional data or until the printer is reset."

Here is the address where you can download the manual:

http://www.xante.com/support/aw3g/manuals/PDF/complete.pdf

Interesting. I tried printing a simple 3-page Excel spreadsheet sent my by a colleague to my 8500DN from Microsoft's Excel Viewer and got a timeout error formatted as follows:

ERROR: timeout
OFFENDING COMMAND: timeout

STACK:

42
-mark-
(84,160)

No idea what this means, but resetting the network parameters (even though I use USB connection) from the printer's front panel cleared the problem. The printer would print nothing else from any program until I performed this reset. Wonder if Excel futzes with settings and printing somehow?