FXGPWIN problems within XP

I am using Mitsubishi MELSEC FX1S-14MR PLCs with SWOPC-FXGP/WIN-FL ver 3.00 1996 software. I have 8 setups in a training lab.

Originally, with the older laptops running Windows 2000, there were no problems running the software and communications were with a serial cable or a USB-serial adaptor. No problems...ran like a charm...everybody is in their happy-place.

Now, with new laptops running XP Pro SP3 using the USB-serial adaptors (no serial port), I have problems. The software, once in communication mode with the PLC, suffers from 13sec response delays roughly every minute. There are also infrequent freezing, "blue screens of death", and rebooting. These are rare but do happen randomly.

I have tried running the software in compatibility mode (W98, W2K, etc) with no change. I have tried running in a separate memory space with no change. I have set the paging file to a fixed value with no change. There is lots of harddrive space and the CPU usage is good. I have disabled other applications including virus protection. These laptops have no access to any network or internet. Nothing I do resolves these issues.

The new XP laptops have no problems with the USB-serial adaptor as proven with other serial communication programs. The software has no problems with the USB-serial adaptor as proven with the original W2K-based laptops.

I have yet to try a different PC with XP or just with SP2. Nor have I yet loaded up an older laptop with XP or a newer laptop with W2K.

Thank you ahead of time for any ideas. Cheers.

Check the USB-Serial adapter drivers, they may need updating now you're running SP3.

I used to use a Belkin USB-Serial Adapter that worked fine with Windows XP. When I changed to a Windows 7 PC recently I found that the same adapter did not work anymore and was unsupported in Windows 7. I had to buy a new adapter (same manufacturer).
My point is, it's all about versions and drivers etc so I would definitely check those first and see if they're compatible with XP SP3.