We have IE6 at work and it scrolls fine with the new and also scrolled just fine with the older format, as well.
It seems to be a problem with IE7 and I see by a google search that others are reporting it with some other phpBB's as well. I did find a setting in IE7 that helps some, but it seems there are some other fixes to the style sheets that some webmasters are doing that helps a lot.
The setting that seems to help a little is Tools | Internet Options | Advanced Tab | uncheck the box next to "Enable visual styles on buttons and controls in webpages"
It seems to be a problem with IE7 and I see by a google search that others are reporting it with some other phpBB's as well. I did find a setting in IE7 that helps some, but it seems there are some other fixes to the style sheets that some webmasters are doing that helps a lot.
The setting that seems to help a little is Tools | Internet Options | Advanced Tab | uncheck the box next to "Enable visual styles on buttons and controls in webpages"