I have downloaded this game TWICE and it passes the integrity check but it fails to install about halfway when it is done. It says during copying the file SALLY_CLEAN.BF "Source file is corrupt" and the install stops.
I am running Vista32 Home Premium Fully patched. 4gb of RAM, over 800 free GB of drivespace.
I've never had another problem with this machine.
I love GOG and this is my first failure. I wonder if it has been reuploaded as obviously others have it working as per the posts here - but I cannot even install...
I've tried disabling AV software, run as administrator, run drive check... it doesn't work.

Did you try downloading it with the "GOG Downloader" ? I may advise defragmenting your hardrive and maybe even checking Harddrive errors with ScanDisk, but you said it was your first failure. So, the file may be corrupt.

Have you tested the same installation file you downloaded with another machine?

Have you tried redownloading the game via your browser?? I downloaded it once and never had any corrupted files...

I have the exact same problem! Except my integrity check fails too.. But it's damn annoying, I already downloaded the file 2 times! (Both times with GOG Downloader). I'm gonna try downloading it with my browser, I hope it works.
EDIT: Ok I just finished downloading it with my browser, still corrupted. sally_clean.bf problem.. So annoying.. Well i'm on a slow internet at the moment (downloads only come 50kb/sec) but I'm gonna get a 10mbit connection soon, so I'll try downloading the game when I have that. Wish me luck!

I've had installation issues as well. I have downloaded the game four or five times through both my browser using the ping method as well as the GOG Downloader and the problem persists. The file integrity check passes every time. The installation starts just fine every time, but when the installation reaches what looks like 98-99.9% it just hangs. No error given, no system lock-up, the installation just sits there at 98-99.9% complete for eternity. A desktop icon even pops up but the installer won't finish or finalize or whatever.

System Specs:

XP Pro fully updated
4GB RAM
GeForce GTX 260 core 216
Athlon 64 X2 6000+ (3.0GHz) CPU

Any help at all would be appreciated...