Notes and Excel 2003 causing problems!

We found something very odd running Lotus Notes on XP. Our clients use some applications that are heavy on DDE. If they try to open an excel or word attachment in Notes, it can take up to 3 minutes! The only fix I found was to go into the File Type section for .XLS files in Windows Explorer and change the Open action under the DDE message window by clearing it out completely. Normally, [open(%1")] is in the DDE Message field but I had to clear this and add "%1" to the "Application to Perform Action" field. This resolved the problem but now clients can not have Excel sheets open within one workbook. This seems more like a work around. Does this sound familiar? any issues with DDE causing issues when opening excel/word attachments in Notes?

Thanks!