A friend of mine was having a problem with his windows 7 machine hanging after boot, it would log into a black screen and never get past. I offered to try and work out the problem, started with a fresh install of windows by formatting the drive and installing the OS again. The only driver I need is the wireless lan, as once it is present I should be able to retrieve the rest. (Note: Though the ethernet driver is present, it is not an option as it is an acer v5-531, which requires an adapter to use an ethernet cable with it's vga/lan dual port. . . weird) Here is a quick summary of events: Download the zip from manufacturer website on a separate computer (vista desktop) Transfer the zip to the laptop Windows fails to extract the directories Try with 7zip 7Zip Reports CRC Failure on a .cab file (the largest one in the zip, of two) Attempted to download the zip again, considering that the PC I got it from may have improperly downloaded the file All file sizes match from step to step, unzip failure persists Download the file from a different PC (win 8 laptop) Transfer new zip with a different USB drive Issue continues to persist Research leads me to https://www.techspot.com/community/topics/crc-failed-everytime-everywhere.60277/ I followed Rick's advice and ran memtest86+ (booted from bios on usb stick) Full test complete and passed I've done some more research on what could cause the issues but my leash is running short. I'm coming here because Rick's suggestion was an interesting one I never would have realised, and hope that the rest of you have insights like he does. All help is appreciated.