I've also found the the eTrex 30 randomly breaks up track data files in the Garmin/Archive directory.  It doesn't save 10,000 points when set to Full as one would expect.  I think the only way to avoid data loss with this unit is to never clear the track log, never save, & use a product like Topofusion to merge the fragmented data mess Garmin leaves behind (if you're lucky).  I'm so frustrated with this unit that I'm probably going to just sell it & go back to using my Vista HCx.  I've found no difference in accuracy between the two units & the Vista HCx never loses track data unless you fill the data card (not an issue with the size of cards today even when recording 1 point per second).

When the Vista HCx is set to save track data to the card, it saves a single continuous track in a standard file format (GPX) in one logically named file per day with ZERO user intervention.  It doesn't get any simpler than that!  Let Garmin know!  KISS!

BTW, here is a link where you can request Garmin add the "Save track data to SD card" feature:

http://www8.garmin.com/contactUs/ideas/

The eTrex 30 is a mess when it comes to recording track data compared to the Vista HCx.  With the Vista HCx set to record to the data card, all your track data is kept in a file named for that day no matter what you do.  There is nothing to remember, it just works.  The eTrex 30 has no option to record track data to the card - it only records to the built-in internal memory.  Big mistake.  It's very easy to lose track data if you don't remember to save or download the data daily!  If you Reset your trip computer & track data each day (a totally normal thing to do), without MANUALLY saving previously "current" track data, it WILL BE LOST, for good... gone.  It really sucks.  A huge oversight by Garmin.

I've written to them requesting they add/enable the "Save to data card" option on the eTrex 30.  Maybe if more people do the same, they'll include it in a future software update.  The eTrex 30 has other features that make it a worthwhile upgrade from the HCx, but this track data issue is a huge step backwards IMO.

The rechargeable cycling-specific GPS devices from Garmin are of no use to me.  I'm not interested unless I can use regular AA batteries I can buy at a gas station!  I have no idea if they deal with the track data better though.  I just can't believe Garmin didn't think this thru.  It is unreasonable to have to manually remember to do things to avoid data loss!