In order to see clan management screen you need to instruct Internet Explorer 9 to use software rendering instead. This option can be set in Control Panel -> Internet Options, then under tab Advanced check box next to "Use software rendering instead of GPU rendering". See screenshot. http://i.imgur.com/0Ts4t.jpg
If you have Internet Explorer 9 installed then this issue is caused by its GPU rendering feature.
You may use a complete diffrent Browser then the Internet Explorer, but Combat Arms is using the Internet Explorer. So the fact of your diffrent Browser usage is irrelevant.