some problems solutions:

Network card
if you need to force set speed of network card:
[code:1]sudo mii-tool eth0 -A 10baseT-FD[/code:1]
this will set settings to 10mbit fullduplex. For 100mbps (default) is it 100baseT-FD. If you dont want fullduplex write HD instead FD in the end of command

Nvidia graphic card + 3d efects
if you installed NVIDIA accelerated graphic driver and enabled special effects via system/settings/desktop effects you are now using gnome window manager - drawer that draws your theme and effects makes compiz. This combination is not ideal because of you can be limited in resolution. And if you will run
[code:1]sudo nvidia-settings[/code:1]
and change resolution, you have to save this change to xorg.conf file. Problem is, that after this operation can your compiz stop drawing themes for windows.
Solution: let download beryl-manager
[code:1]sudo apt-get install beryl[/code:1]
and add it to session for automatic run after startup. Install emerald
[code:1]sudo apt-get install emerald[/code:1]
start beryl
[code:1]beryl-manager[/code:1]
you will see red diamond nearby you system o´clock. Use rightclick and after click to 1st option you can administrate all graphic effects and turn on/off many functions. Click to "select window manager" and check if you have selected beryl. Now check option "select window decorator". Turn on option "standard beryl decorator (emerald". You still dont see borders around your windows. Now check option "advanced beryl options" - > "rendering path" and turn on "copy"[/b]