Product Firefox Release Channel release Version 49.0.1 Build ID 20160922113459 OS Windows 7 OS Version 6.1.7601 Service Pack 1

Signature: chtbrkg.dll@0x1beb1

chtbrkg.dll = unknown however chtbrkr.dll = Microsoft Chinese bigram character breaker for Index Server

This is for Sumo's Related Bugs 1290403 NEW --- Crash in chtbrkg.dll@0x2e1f0

I just looked over the bug report.

chtbrkg.dll may be an add-on; Internet Download Manager integration It is thought it could be malware or adware.

Do you have that add-on?

You may have ad / mal-ware. Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up.