So I had never exported with XML tags before but I quickly mapped my styles to tags and tried it with the working files I had used from a book I had previously exported to epub and it exported within minutes with no problem (given, the epub didnt look very pretty), but ID5.5 didnt crash on me. Are you embedding any fonts by chance? I know this plagues people in the #eprdctn group on twitter quite a bit from just exporting normally to epub from ID5.5.
Also, with ID5.5 you dont need to break up the file to make the ePub, just generate a TOC with the Para style you are using for your titles and when you export, check the box next to “Break document at Paragraph Style:” and choose the same Para style you generated your TOC with and you will get separated files, a linked ncx, and all the files listed in the opf.
I havent used the article pane before so I cant say whether or not it will work any better for you.
And for reference, I am on a Mac running ID5.5 on OS 10.7.2.