The Jopr logo on the login page and then in the menu bar has reversed background, making the image rectangle visible.
In general the icons have visible backgrounds...
Can you specify which pages have this issue? In general the fix I have committed waits for the page to load and then performs the fix on the transparent png files.
I do not see this issue on ie6, rev3752.
Can't reproduce
This bug was previously known as http://jira.rhq-project.org/browse/RHQ-1965