Snow Leopard and Time Machine - Progress counter not working properly

[RED™]

I've searched the web and the forums but I do not find anything that matches my problem, here it is.

I'm using 1 Time machine drive (WD My Passport Studio 500 GB FW 800 for Mac) for my two machines, MacBook Pro (June 09, upgraded from Leopard with Snow Leopard Up to date disc) and my MacBook white (Late 2007, upgraded from Leopard with Snow Leopard retail disc).

On my MacBook white, when I plug in the TM drive via USB, and when I click on the TM icon in the menubar, it says "Calculating changes (or similar)... (1, 2, 3, and so on %) until 100 % and the backup works just fine.

But when I plug my TM drive onto my MacBook Pro (via FW), it says "Calculating changes... 1%" and it remains stuck on those 1%, but then after a while starts the backup properly.

ANyone noticed this too? What can be the causing this?

 

[Corrode]

Yeah, mine will calculate changes sometimes and say it needs to write, say, 1GB, and then once it reaches 1GB, continues writing for another several hundred megabytes, adding to the total of what it originally estimated. I don't really understand it, but as long as it's backing up my computer, I don't really care.