Download this tool:

http://www.tesnexus.com/downloads/file.php?id=39550

Edit GameCompanion.ini, and add a line with TESV.exe under the [AutoFFMode] section. Then run GameCompanion.exe.

Run Skyrim, then on the launcher screen, go to Options, select Windowed Mode, then change the resolution to the full resolution of your monitor (should be the bottom entry in the list).

Now when you're playing Skyrim, just pause the game by hitting Escape, then alt-tab out and the game won't crash! Enjoy!

(Not my mod, found this when playing Oblivion)

Windowed Mode, even borderless, uses more resources.

By crashes I assume you mean where it appears to hang? Just hold Alt and hit tab until you select Skyrim a second time - it loads back up fine.

What quick said. You just need to click back into the game via alt tab

I agree, using the GameCompanion mod did reduce the graphics noticeably. Oh well, forget what I said.