How often do you reformat / reinstall. in Windows 10 Posted June 23 Mostly when I build a new PC or do a major upgrade, or when there's an all new Windows version. I have in the past migrated a Windows install to completely different computers but that pretty much ended with XP. In the 1990's I migrated a Windows 95a install to five completely different PCs. I'd have all the drivers for the new (or new to me) hardware, then in Device Manager I'd uninstall everything it would allow, then shut down. Move the hard drive to the new computer and boot up. Then install the new drivers and it was good to go. It was also far far easier to migrate 9x to a new hard drive. Basically it involved moving the swap file to the root then copying and pasting all the drive contents except for the swap file and a couple of others in the drive root. Swap the new drive in place of the old, boot up and all would work. But that 95a transplant series came to a halt when by crazy coincidence it got one character corrupted in the Registry that caused the weirdest behavior I have ever seen in any version of Windows. In Explorer I could single left click on three folders or files, one after another and it would crash Explorer. This was made especially annoying because the corruption somehow happened the instant I changed the default Critical Stop error sound to a breaking glass effect. No Registry tools I tried could fix the error. Regedit would not allow the corrupted entry to be deleted. Doing the command prompt Registry export and re-import to purge unused information would fail. I even reinstalled Windows over itself, which in 95 would bulldoze over many problems by replacing them with the default files, leaving most installed software working. But not that one, the corrupted entry happened to be one that an install over itself didn't over write. (Doing this with Win98 was mostly futile because it preserved much more than 95 when installing over itself.) So I found a 3rd party file manager that allowed for copying off all the files I didn't want to lose so I could do a clean install.