I am getting this error. It seems to happen around the tool change sequence. The program still runs and works, this was just popping up repeatedly. Retry does nothing and just pops this up again. Pressing ignore lets the window go away and things resume as normal, but it will pop up again.

Debug Assertion Failed!

Program: C:\Mach\Mach3.exe
File: fclose.c

Expression stream is NULL

For information on how your program can cause an assertion failure, see the Visual C ++ documentation on asserts.

(Press Retry to debug the application).

Any ideas what is causing it?

I know this is not a lot of information for troubleshooting, but please ask me any questions that might help.
I notice my mouse stops working repeatedly making beep also, not sure if that is related. It does not happen at the same time, so I doubt it.
I am using the latest version of Mach 3 on a Windows 7 fast computer and Ethernet smoothstepper. No problems with machining or crashing or anything that I know of, it still ran the program through fine other than clicking ignore on this.

You need to backup what special files you have created including the XML . Then Delete Mach3 completely and Reload a brand new copy.

(;-) TP

I always keep a backup of the XML, but what other files would be needed? What about my plug-ins (ESS, pokeys, etc)?
This does not sound fun. I hate to redo everything. I just got it running good and this will surely consume a precious night of time

Also, could you elaborate on what is going on and why the reload is necessary?