Try the following. First, disable Steam Cloud for Train Simulator. Next, locate and delete the following files, make backups (assuming default installation paths): C:\Program Files (x86)\Steam\userdata\<your id>\config\librarycache\24010.json C:\Program Files (x86)\Steam\userdata\<your id>\24010\remote\career.xml C:\Program Files (x86)\Steam\appcache\stats\UserGameStats_<your id>_24010.bin C:\Program Files (x86)\Steam\steamapps\common\RailWorks\Content\PlayerProfiles.bin C:\Program Files (x86)\Steam\steamapps\common\RailWorks\Content\SDBCache.bin C:\Program Files (x86)\Steam\steamapps\common\RailWorks\Content\TMCache.dat See if it works and let me know. Everything should be reset to zero. Cannot guarantee it though (I won't try myself)
Fair enough. There might be more files hidden in the Steam folder... or the XP is linked to your SteamID on their servers... Why not drop a few lines to Steam support?
The answer is very formulaic - disable the cloud, delete the folder from the game numbers in userdata, then re-enable the cloud