Well it might if you are using a bad proxy script
Let’s assume that you use some sort of browser detection script, IE10’s Agent String might cause your script to act weird and may crash. However, if you block IE10 at the proxy and force the client to run IE10 in IE7 compatibility mode then it works just fine.
In my humble opinion, If a User Agent string can crash the proxy, then surly you have a bug. A bad bad bug indeed leaving you wide open for a DDOS attack..! This is scary because the User Agent string can be manipulated easily.
One way to look at this is by checking the User Agent RegEx:
IE 10 User Agent String: Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.1; Trident/6.0)
I presume that your proxy is using something like /MSIE\s(\d)/ and the extra digit is killing your script..! I would use something like this instead: /MSIE\s([\d.]+)/