I stopped playing and working on BF1942 for a while because every time I started the game it would be stretched to my 1920x1080 screen instead of keeping its aspect ratio from the 800x600 resolution.
After messing around with display drivers and AMD Catalyst Control center, and failing, I gave up for a long time and played War Thunder to relieve stress. Good news though, I dunno where I read this but I saw a one-line hint from someone that it could be a setting on the computer monitor itself. So I opened up my (HP) monitor's settings and went to Image Control then Custom Scaling and sure enough it was set to Fill to Screen instead of Fill to Aspect Ratio. So far it is working for me.
I only realized this setting just now so I don't know how/if it will affect any other games I play. Hoping this is the real solution.