General check list
1) Pirate windows. We cant help you with that. Bugs in OS are out of our interests in the game development. Buy an original version with all the updates. Or if not, then try linux and wine. Pirate windows is one of the main reasons, why pp2 is not working.
2) Old drivers. Update them and follow manufacturers instructions. Do not install them by "click and pray" method. If clean install is requested, do it so. Moreover, you motherboards drivers may need update too.
3) Adjust your graphics adapter settings. Let them be in "game decides" mode. In optimization, try different things and learn how they effects.
4) Try old drivers. Sometimes they may work better than new ones. New versions of drivers may have bugs too.
5) Open settings.dat file (show hidden folders, c:\ --> program data --> procyon --> etc) with notepad, change game resolution to 640x480 and save the file. Now the game works in the old resolution.
6) Random crashes may be due to net traffic problems. Try to host with smaller amount of players.
7) Try to solve the problem by yourselves. There are several possibilities behind the problems, varies from bad wlan drivers to virus-detecting softwares. We cant help you all, it is your own computer with your own softwares and hardwares. Sorry. Most of the players have no problems. We gain no salary by creating the game and it is freeware. We just dont have more resources to make it better (or it just takes more and more time).
8 ) Remove ALL of the over-clockings from ALL of your hardware/software set-ups. This may help you when facing strange problems.
9) Open your computer and clean it up. Use carefully a vacuum cleaner or air pressure to remove all the dust from fans and coolers etc.
10) Launch virus detection softwares. Try several different types of them. Like antivir, f-secure, norton etc.. and try even those online-scanners. Once panda-online scan found one virus, which was not found by any other used. Also check adware, spyware etc and even rootkit revealers. But do not let them do anything you dont know what it will effect. Just call your nerd friend and let him do it. Check you systems task list and shut down processes you dont need. Check automatic start ups and remove all of those you dont need (e.g. automatic update checkers etc). Unistall softwares you dont use anymore. Remove extra shortcuts from your desk. Run ccleaner to clean old and useless things from your registry. Defrag your hard disk. etc etc..