Useful Troubleshooting software for Windows

Some free not open source (F only) and some free open source software (FOSS) that I find useful, maybe you will too:

for regular users

• systems information for windows siw
• sysinternals what's run at startup autoruns
• what has what files open   unlocker
• disk space usage WinDirStat
• capturing screen images from your computer mwsnap 
• image and photo editing software Paint.NET

for power users / admins

• tweak your TCP/IP settings Doctor TCP from dslreports
• sysinternals task manager with much better detail and control  process explorer
• what happened after a crash (blue screen of death) bluescreenview
• what has what files open OpenedFilesView
• create bootable live USB drives unetbootin