When I play The Sims 2 Open for Business Expansion Pack, I play for a couple of minutes and then the game shuts down and this message comes up: "The Sims 2 EP3 has stopped working. A problem caused the program to stop working correctly. Windows will close the program and notify you if a solution is available."

SOURCE: WHEN I TRY TO PLAY THE SIMS COMPLETE COLLECTION

because you are using vista

SOURCE: Sims 2 installation

You must install the expansion packs in a semi-fluid order. That is, there was an order they were released and for best results, you should install them in the same order.

http://compsimgames.about.com/od/expansionpacks/qt/sims2_exporder.htm

The above site is the order of the expansions. Keep in mind, it starts at the top and goes down (oldest at top, newest at bottom). You must use the latest most expansion pack's disc to play. That means, if the last expansion pack you have is "Seasons", you will need to use that disc to play the game.

Due to copyright laws, I'll be unable to assist you in how to play the game without the need of the discs but in essence, the above information will at least get the game installed with the expansions in the proper order. You and your friend may just be unable to play the game at the same time.

SOURCE: Installing Sims 2 expansion pack

For The Sims 2, go to My Documents\EA - and copy the "The Sims 2" folder and paste it somewhere else on your computer. You can rename it to "TS2 Backup Original"... then add one expansion and then do the above again (copy/paste the "The Sims 2" folder) and rename it to something like "TS2 Backup University" (or the name of whatever expansion you're adding).

But realize that these backups will have your people and neighborhoods EXACTLY as they were at the time you copied them. So if you install an addon (or 6) and then play for 3 months, and then decide you want to go back to a previous backup, you WILL NOT have all of that work that you've done.

If you have the hard drive, space, though... I would recommend making a backup after each expansion addition... and then make a backup once a week or two to save/backup your progress. Also, if you download a ton of custom content, like me, keep a copy/backup of that folder with your other backups. =)

Good luck and have fun!

SOURCE: I lost my Sims 2 Nightlife expansion pack code for

If you bought it online ,you could request the code again ,but each CD has a unique code.
I'm afraid you will have to buy another one or ask a friend who has the expansion pack to lend it to you.