blank email inbox panel in 5.2.0a and IE7? Ok on Firefox

[tpine]

We're observing persistent (day-after-day) problem in displaying the Inbox (the upper right) panel of the 3-panel Email in IE7. The Sugar version is 5.2.0a. This problem only happens in our client's office with regular DSL connection to the Internet.

The blank panel problem does not exist in Firefox 3 on the same PC. But they don't think the Firefox is necessary for an 'upgrade'.

We cannot reproduce the same problem on our PC (dual-core) loaded with IE7.
After a few searches in the forum, we cannot find anyone reporting the same problem.

Also they are not happy with the 'slow' email page in the 5.2.0a version. They were using 4.5.1 until recent upgrade.
Should we change some out-of-box parameters to tune the 5.2.0a on the server (Fedora 10)?

Thanks a lot.