The PC gaming platform is more prone to having more bugs in games (games not working as they should) over consoles for several reasons:
1. The platform is not uniform. This means someone has issues with drivers and so on, or some odd BIOS, then a game may not load. It also means that developers won't be able to test software against every possible configuration to see if it will work.
2. Consoles, when you game, are just doing gaming stuff, or basic stuff embedded in the operating system, such as notifying that friends are on. With the PC, you are running firewalls, anti-virus and other things to. These can cause memory conflicts. Factor in also how PC gaming is subject to piracy, and anti-piracy measures causing some games to not load. Multitasking = greater chances at failure, crashes and bugs.
3. PCs end up having various installs that update the internals of the operating system, in a manner than isn't uniform across all PCs.
End result is you are more prone to having buggy software on the PC, due to how a PC is made.