Symptoms: Cannot boot neither Windows 7 nor Ubuntu after Ubuntu installation. Netbook locks up just after POST. Even the recovery partition isn't working.

Cause: Looks like Ubuntu (GRUB) overwrites some important boot sector stuff.

Fix:

1) Get the Ultimate Boot CD and install it on a USB stick (use Google). Use the HDD option and select any boot manager that let's you choose and boot your original Windows 7 boot loader. Use F8 to enable extra options and boot into the Recovery Mode. The automatic stuff doesn't find anything to fix so you'll have to do it manually. Open a Command Prompt and use bootsect.exe to install a fresh boot sector and MBR to your system partition.

2) The recovery partition is probably still not working. Boot into the recovery partition using UBCD. When it is loaded, press CTRL-ALT-F10, type the password secos. Go to the Tools-tab and create a disk. Now you have a Samsung USB Admin tool. Boot with the newly created tool and select MBR Fix. You should now have working working Win 7 and Recovery partition again.

3) Adding Ubuntu to the Windows boot menu is left as an excercise to the reader (there are plenty of guides for that, use Google). Now you can boot Ubuntu too!

Your boot sector will break every time Ubuntu decides it needs to update GRUB. Fuck.

Links:

http://www.ultimatebootcd.com/
http://www.sammynetbook.com/forum/threads/13251-Story-about-a-samsung-N210-03ES-the-F4-and-MBR-the-recovery-solution-4.0.0.42-and-HIS-admintool
http://www.sammynetbook.com/forum/threads/12024-N140-SRS-Partition-Admin-tool-made-F4-functional-again.