If you're having trouble with losing your save file, you can back up the save on an external drive or somewhere else. It helps just in case you delete it with CCleaner, or with something else. Make sure you back it up in a place that won't get deleted, or the whole thing's kinda pointless.
The location of your save varies depending on the site you play on and your operating system. Valthero, a user on MnB.net made a very nice guide on how to find your save file:
Windows XP:MnB.net
[LOCAL DISC]\Documents and Settings\[USERNAME]\Application Data\Macromedia\Flash Player\#Shared0bjects\[WILDCARD]\games.mochiads.com\c\g\mud-and-blood-2\mudandblood2.swf\mnb21.sol
Windows XP:Kongregate
[LOCAL DISC]\Documents and Settings\[USERNAME]\Application Data\Macromedia\Flash Player\#Shared0bjects\[WILDCARD]\chat.kongregatecom\gamez\0002\1802\live\mudandblood2.swf\mnb21.sol
Windows 7/Windows Vista: MnB.net
[LOCAL DISC]\Users\[USERNAME]\AppData\Roaming\Macromedia\FlashPlayer\#Shared0bjects\[WILDCARD]\games.mochiads.com\c\g\mud-and-blood-2\mudandblood2.swf\mnb21.sol
Windows 7/Windows Vista: Kongregate
[LOCAL DISC]\Users\[USERNAME]\AppData\Roaming\Macromedia\FlashPlayer\#Shared0bjects\[WILCARD]\chat.kongregate.com\gamez\0002\1802\live\mudandblood2.swf\mnb21.sol
Windows 7/Windows Vista: Downloadable Client
[LOCAL DISC]\Users\[USERNAME]\AppData\Roaming\Macromedia\FlashPlayer\#Shared0bjects\[WILDCARD]\localhost\FromMemory\[WILDCARD]\100\[WILDCARD].swf\mnb21.sol
Finder\[USERNAME]\preferences\macromedia\flashplayer\#Shared0bjects\[WILDCARD]\games.mochiads.com\[WILDCARD]\[WILDCARD]\mudandblood2\mudandblood2.swf\mnb21.sol
If you have trouble finding the save file, try showing your hidden files/folders, and/or searching for "appdata" or "%appdata%" in your "Run" dialogue.
Back on track: simply copy mnb21.sol to wherever you wish to store it. If you lose your data, simply copy that back to the original folder. I usually copy the file after every deployment, just to make sure I don't lose any progress.
This method may also be used to transfer your .sol between personal computers. Copy the .sol to a flash drive or send it over the Internet, download the file to the computer that you wish to have it on, and voilą, transfer complete.
All credit goes to Valthero.
It no longer seems to be unfair random brutality; it's still unfair brutality, just now it's consistent. My last few games have all ended thanks to eerily accurate PAK38s showing up at wave twenty, ignoring any and all gunfire, and blowing my shit to shreds.
If early paks are a problem, try placing a bunker on the field and keeping your troops in there for protection. There's a very low chance for the pak to blow up the bunker, and only happens when the pak round hits dead center.
I get bunkers; by the time the PAKs show up, I've already got a decent building setup with gunner & officer in the bunker, 4 soldiers and engie in trenches in a line adjacent to the bunker, and medic wherever the wounded are. If I stick all my soldiers into the bunker for protection, the firerate malus is enough that the PAK never actually gets killed, and all the enemy soldiers spawning just waltz right on past
Gunners are a good unit to put inside bunkers, because they suffer no reduction in reaction time, so they fire the same inside a bunker as outside. Gunners can help shoot the crewmen off the pak, and will sometimes even completely destroy the pak. Also, since paks generally shoot at the closest thing to them, you can place bazookas or AT guns, or other Anti-tank weapons behind your bunker so they can kill the pak, and the pak won't shoot at them.
The difference between the downloadable (2.2.7 from what i have read) and latest online version ( 2.3.1 according to wiki) are detailled there:
http://mudandblood.net/html/modules.php?name=News&file=article&sid=78
Yeah, urb hasn't released the newest downloadable version yet. The latest version so far is 2.2.7c. The current version, 2.3.1g, is still somewhat buggy, and contains some balance issues which are still being worked on, so after a few patches, hopefully a new version will become available for download.