Microsoft offers a suite of utilities called Sysinternals for free for troubleshooting your PC. The suite is far superior to many of the alternate freewares that are available.
Mark Russinovich, now a Fellow in Microsoft, originally developed them along with Bryce Cogswell when they were in the company Winternals Software. The company subsequently was acquired by Microsoft in mid 2006. Initially, many of the tools were not just freeware but were also accompanied with the source code. No longer, of course.
The utilities are categorized under File and Disk utilities, Networking utilities, Process utilities, Security utilities, System information, etc. The Windows Sysinternals …read more

PuTTY is a free Windows client that allows users to log into remote systems through raw, Telnet, SSH, remote login, and serial connections. It is primarily used for logging into UNIX systems through Telnet and SSH, and at 444KB (direct executable) is  very popular with UNIX lovers even though its last version of 0.60 beta has not been updated in nearly two years.
I recently discovered that there is a tabbed version of PuTTY called the PuTTY Connection Manager allowing multiple PuTTY instances in a single window.

PuTTY Connection Manager has several other features like workspace customizations, auto-login and post-login commands, Import/Export …read more