You can set the max file size between 512MB and 2GB (not 2 hours!!) in the project menu (this may have been moved to the System Defaults menu as of v1.04 - I don't have my HDP2 handy to check). It should default to 1.5GB.
If you are recording at 24 bit/96 khz you generate 33mb of data per minute and you would get a new take every 15 minutes with the max file size set to 512Mb, or every 60 minutes with max file size of 2Gb.
The HDP2 will also start a new take if you press the record button while you are recording. It's pretty handy if you want to seamlessly start a new take at a specific point, but could be causing your problem if you aren't aware of this behavior. This was introduced in v1.04 and is mentioned only in the firmware update release notes.
cheers
Paul