The max number of open files was set in the CONFIG.SYS using the FILES= entry.
The default was 20 (of which DOS itself reserved 5). Normally this was set to 40 or 50 for ProIV.

I also found an article on locking (see
http://support.micro...&NoWebContent=1

This refers to NT and SBS but may also be relevant to XP. Have you tried looking at Microsoft support?

Ok, I just found the following site on Google.

http://www.experts-e...Q_20937717.html

It claims to contain the response to the following question:
"I have a DOS program that requires config.sys be updated to read files=120 and buffers=30. I did this using msconfig but the program still does not run and returns the same message. I have corrected this before a year ago but just upgraded an old system with new hard drive and XP and forgot the correct method."

I can't be bothered to register to read it - but it may be helpful?