I am running EasyTutu with a few additions, namely:

Tutu Degreenifier
Tutu GUI
Widescreen Mod (1280x720)
Unfinished Business
1PP
- Core paperdolls
- Extended palette entries
- Female dwarves
- Thieves galore
- Legacy shields
- Core updates and item patches

This setup works great on my Windows 7 x64 machine. Recently I got a Windows 8 laptop. I didn't want to go through all the steps of modding the game again so I copied the entire EasyTutu directory to the laptop's hard drive. I can launch the game, watch the opening videos, and select the game to load. But as soon as the loading screen appears, the game crashes with this error:

Baldur's Gate Error: Media Removed From Drive
Please Insert Baldur's Gate CD-1 Into CD-ROM Drive

What should I do?

Edit your Baldur.ini so that the Alias section shows the correct path to the data files

Ah, that would explain it. I didn't even have BG2 installed. However, I do now, the paths are correct, and I'm still getting the same error. Here is the relevant portion of baldur.ini:

[Alias]
HD0:=C:\GOG Games\Baldur's Gate Tutu\
CD1:=C:\GOG Games\Baldur's Gate 2\data\
CD2:=C:\GOG Games\Baldur's Gate Tutu\data\
CD3:=C:\GOG Games\Baldur's Gate 2\data\
CD4:=C:\GOG Games\Baldur's Gate 2\data\
CD5:=C:\GOG Games\Baldur's Gate 2\data\
CD6:=C:\GOG Games\Baldur's Gate 2\data\

Edit: This happens on a new game too.

Are you sure it is the same error, & not asking for CD2?

CD2 should be in
CD2:=C:\GOG Games\Baldur's Gate 2\data\