Could be simply poorly written coms routine depending on the PC's clock - "significant" (even a minute would be significant in this case) change / jump in the time would make it (to think) the connection has timed out and spit out the 90000 error. Or it could be some "clever" way of preventing hacking / spoofing / redirecting who-knows-what ... However during the DST change it might not happen as you're simply (in principle) shifting the time zone while leaving the actual internal / OS clock untouched - you can try to test it by changing the time zone or DST settings now manually to know for sure.