Duplicate headers in response

This problem seems to have started a few days ago without any code changes, my local tomcat server would just stop responding.

My main filter breakpoints don't get hit, and only some resources get loaded.

The ones that do fail, seems to have duplicate response headers:

Accept-Ranges:bytes
Accept-Ranges:bytes
Content-Disposition:inline;filename="online-framework.js"
Content-Disposition:inline;filename="online-framework.js"
Content-Encoding:gzip
Content-Encoding:gzip
Content-Range:bytes 0-42062/42063
Content-Range:bytes 0-42062/42063
Content-Type:application/javascript
Content-Type:application/javascript
Date:Tue, 19 Apr 2016 13:01:18 GMT
ETag:online-framework.js_42063_1461060446000
ETag:online-framework.js_42063_1461060446000
Expires:Tue, 26 Apr 2016 13:01:19 GMT
Expires:Tue, 26 Apr 2016 13:01:19 GMT
Last-Modified:Tue, 19 Apr 2016 10:07:26 GMT
Last-Modified:Tue, 19 Apr 2016 10:07:26 GMT
Server:Apache-Coyote/1.1
Server:Apache-Coyote/1.1
Transfer-Encoding:chunked
Transfer-Encoding:chunked
Vary:Accept-Encoding
Vary:Accept-Encoding

And chrome stops with an error: Failed to load resource: net::ERR_INCOMPLETE_CHUNKED_ENCODING, which makes sense.

The tomcat connector has not been modified and does include a gzip response. what have I tried:

• thread dump - no obvious blocking code
• wireshark - don't know it good enough to figure out what goes wrong
• disabled antivirus
• no proxies running

The page just seems to load forever. Here is the kicker, it happens randomly, it would start working one hour but not the next.

The only thing I can thinl of is that some domain thing may have changed, no windows updates have run, and 3 or 4 other pc's do the same thing while 2 others do not (same build)

I have no idea where to look next? Any ideas?