Hi, Hopefully this is the right forum to post this in. I've tried Googling and searching for threads on checksum mismatches, but haven't been successful. I'm trying to replace Explorer.exe for a custom Win2k installation, but makecab.exe doesn't seem to re-compress explorer to the original size. The original (Win2k SP4) Explorer CAB file (EXPLORER.EX_) is 91.7 KB (93,929 bytes). I'm just changing 3 bytes at $88EEh, $14E28h and $14E36h from 0x01 to 0x11. Which makes Windows 2000's system tray have 256 colors, instead of the original 16. But when I try to recompress explorer.exe (same filesize), makecab.exe (Version 5.0.2147.1) makes it 8KB~ larger. Here's the output. Microsoft (R) Cabinet Maker - Version 5.00.2134.1 Copyright (C) Microsoft Corp. 1981-1999. 0.00% - raw=0 compressed=0 13.46% - raw=32,768 compressed=20,645 26.92% - raw=65,536 compressed=38,642 40.38% - raw=98,304 compressed=57,786 53.83% - raw=131,072 compressed=68,456 67.29% - raw=163,840 compressed=74,228 80.75% - raw=196,608 compressed=81,868 94.21% - raw=229,376 compressed=93,723 100.00% - raw=243,472 compressed=102,025 ** EXPLORER.EXE placed in cabinet EXPLORER.EX_(-1) on disk 100.00% [flushing current folder] The new EXPLORER.EX_ is 99.7 KB (102,162 bytes). So my question is this: Does Windows 2000 installation check the filesize/crc32 checksum of each file before it tries to install them? If so, what file do I modify so that Win2k doesn't check this. Or how do I stop Windows from checking this altogether (like disabling SFC for example).