Ajax Viewer hangs when loading maps with tiled base layer groups in IE6

[wct]

I'm having an issue with the 1.2.0 RC1 release when using the AJAX viewer with a map that contains a base layer group. I have a map with a single base layer group containing 10 layers. When rendering the map, IE6 hangs up while pulling down the base layer group tiles from the server. The same map renders correctly when using IE7 or FireFox. If I use a HTTP capture I can see the browser issues:

GET /mapguide/mapagent/mapagent.fcgi?OPERATION=GETTILEIMAGE&VERSION=1.2.0&SESSION=66bc0a1a-0000-1000-8000-0003ffcc28b3_en_0A0032280AFC0AFB0AFA&MAPDEFINITION=Library%3A%2F%2FWCT%2FARC%2FARC_PipeWatch.MapDefinition&BASEMAPLAYERGROUPNAME=Base%20Data%20_PRE&TILECOL=19101&TILEROW=7472&SCALEINDEX=0 HTTP/1.1

GET /mapguide/mapagent/mapagent.fcgi?OPERATION=GETTILEIMAGE&VERSION=1.2.0&SESSION=66bc0a1a-0000-1000-8000-0003ffcc28b3_en_0A0032280AFC0AFB0AFA&MAPDEFINITION=Library%3A%2F%2FWCT%2FARC%2FARC_PipeWatch.MapDefinition&BASEMAPLAYERGROUPNAME=Base%20Data%20_PRE&TILECOL=19101&TILEROW=7473&SCALEINDEX=0 HTTP/1.1

GET /mapguide/mapagent/mapagent.fcgi?OPERATION=GETTILEIMAGE&VERSION=1.2.0&SESSION=66bc0a1a-0000-1000-8000-0003ffcc28b3_en_0A0032280AFC0AFB0AFA&MAPDEFINITION=Library%3A%2F%2FWCT%2FARC%2FARC_PipeWatch.MapDefinition&BASEMAPLAYERGROUPNAME=Base%20Data%20_PRE&TILECOL=19101&TILEROW=7474&SCALEINDEX=0 HTTP/1.1

But then stalls (5+ minutes). If I pull these URL's individually on their own, the server returns imagery very quickly (so I believe the problem is in the javascript on the client). I've been able to reproduce this on several machines running IE6.

[tomfukushima]

Moving to 1.3. Strange that IE6 performs differently, but not unexpected.

[tomfukushima]

Hi wct, Please retest with MGOS 2.0.

[tomfukushima]

No response. Closing.