My Summa T750 cutter may have incorrect settings

Taking a shot in the dark that someone else here may have the same cutter and can let me know why this is happening.
Or if you don't have the same cutter maybe you had a similar problem and can tell me what fixed it.

Now don't laugh - I'm still using Windows XP Pro with service pack 3 on this computer. It runs Signlab 5 just fine.
I have it hooked up to a pre-usb Summa T750 through a Keyspan serial to USB converter.

Since I hardly ever use this cutter, I can't remember if the problem started when I connected it to the USB converter.
I changed the computer this used to be hooked up to and this marginally newer one doesn't have a serial connection.

The problem I'm having is when I send a job to cut or draw, it starts and stops constantly. It seems as if it is not sending the whole job to the cutter or maybe the job isn't being put into the cutter memory.
It won't just start and continue drawing or cutting until the job is finished (like it used to do, very fast btw).
So something changed and I'm not sure what.

I looked at the Com port settings and handshake options are none, hardware, X on-X off. I have tried them all with little to no difference.

Is there a communication setting in the Summa T750 on board menu that I may have incorrect?

Was it Serial or does it also have a Parallel connection? Sometimes the adapters you buy to convert USB to whatever don't work right. Do you have the Install disk for the adapter? You might try here > ://www.vinylforum.org/smf/index.php

This cutter has only the serial cable connection. I've connected it using the Keyspan serial to USB and also connected it without the adapter to the same computer on serial port connection on back which I didn't realize was there. Duh! Regardless, both connections result in the start/stop cutting so maybe it's the computer or maybe it's the memory within the cutter.
When I run a test cut that's in the cutter's firmware, it zips through it without stopping.

The serial to USB converter is unable to keep up with the data rate coming from XP, on the older plotter which is expecting serial data from a Windows 98, 2000 or ME pc. I haven't used my plotter for a long time but still have an old 98 tower to run the old 2003 Graphtec.