This is a known issue that our developers are working on. The "My tickets" screen of eHD includes special meta data that specifically instructs the browser not to make cache, and instead request a new page.
These tags look like this:
<meta http-equiv="Pragma" content="no-cache"/>
<meta http-equiv="expires" content="-1"/>
<meta http-equiv="Cache-Control" content="no-store"/>
It seems that in some cases IE9 will respect these tags, but ignore them in other cases (and create a cache). It is most likely a bug or network setting that causes this, but it is not something GroupLink can fix.
The current workaround is to press F12 and choose Cache -> Always refresh from server. This developer setting will override any other setting in IE.
Also, in Internet Options, under Browsing history, then Settings, make sure "Every time I visit the webpage" is checked under "Check for newer versions of stored pages:"