Ok, so you can’t directly file a bug. Just imagine the number of random noise/issues (“my computer is slow” – well if you didn’t install that crapware you did last week maybe it wouldn’t be?) we’d have to go through daily just to keep up with the volume. Believe it or not , the team that services and maintains Windows after it has shipped is pretty small, and our bandwidth would probably be exhausted just deciding which bugs are worth investigating if we opened the floodgates.
The good news is however, that you can leave feedback. We don’t necessarily read each and every piece of feedback, but my team and I do look at trends and emerging issues, and investigate based on that. After we’ve gotten enough information about the issue, we might fix it and deliver it to the world, usually through Windows Update.
Here is the link to leave feedback about Windows 7