Thout I would post this here, as it is the most relevant thread for this particular mouse, and ohters may come across this problem:
If you own this mouse and need to replace the re-chargeable batteries, make sure you buy batteries that can fully charge at the 1.2 mA current of the charging stand. Logitech only specifies capacity of the batteries that will work, so read the side of your replacement battery before you walk out of the store to make sure they will fully charge on this stand. I tried some Wal-Mart high capacity batteries that work great in other devices, but they never fully charged, so the mouse died constantly.
As a testament to Logitech's excellent customer service, after I called to ask about this, the tech told me that I qualified for a free upgrade to the MX1000 mouse and will send one out to me, even though I have owned the MX700 for at least two years now.