Evening,
New member to this great site, but I'm having this same problem with various ROMs I've downloaded, wish I'd noted before and made a list.
I downloaded
Atari-ST-Demos.zip from Atari/Single-Download-Mega-Packs.
The 285MB Atari-ST-Demos.zip unzipped fine, but I noticed that some of the zips within would not decompress.
A few examples are:
Ambition (1994)(Crystalic).st
Bird Mad Girl Show (1992)(Fraggie's).st
Cor Blimey Megademo (19xx)(-).st
Decade Demo (1990)(Inner Circle)[Preview].st
Tried a couple of different unzippers, all fail.
7Zip says
Unsupported compression method for 'Decade Demo (1990)(Inner Circle)[Preview].st'Latest version of WinZip 17.5 gave:
Extracting Decade Demo (1990)(Inner Circle)[Preview].st
Central and local directory mismatch for file "Decade Demo (1990)(Inner Circle)[Preview].st" (compressed size - local: 350835 central: 351180).
Severe Error: Local and central compressed size values don't match.Windows XPs built-in extractor says something like unexpected end of file.
I have had the same on a couple of MAME roms and Atari ST game roms I've downloaded, but didn't think about it any more at the time.