The development of 'Invasion of Britain' is ongoing, with Coop mode being added. It has been tested extensively. Older operating systems or hardware have had issues. You may fall into this category, I know you play DC but this one map is more resource heavy than that actually.
The best help I can offer here is letting you know that no errors were likely on your end so you can stop fiddling with things. This release leaves a small fraction of Battlefield 1942 capable users behind. Your specifications are desired for future releases and debugging by the development team.
We, thankyou for trying. This installer covers everything on the server, for those who want to attend events on that server please download with confidence! Within this package there is a Santaland map named SL_Woods. It is not in rotation on the server but left within the mod package. If selected your PC is likely to act like you just added Nitrous Oxide to the Carburetor and you will be looking for the power switch. Much worse than than the potential error message the 'Invasion' map may display. We have consistently served the Santaland Mod which in fact never left the Beta stage. One small map file left behind by the original developer that doesn't quite work is left in time for a future developer to see, and fix.
It is in that spirit that this package is offered.
We're anxious to get as many players as possible for this new map while it is being served!