I get a Time Machine Error of "Unable to get status of backup volume".
That's an unusual one. TM can't find or can't mount the drive, or is having trouble reading it.
Is the drive formatted correctly? If in doubt, see Time Machine - Frequently Asked Question #5.
If so, be sure all plugs are snug and secure, and the cable is not frayed, etc. Try a different port and cable (if you only have one cable, try swapping ends -- sometimes a plug that works well in one port won't quite make good contact in another).
I bot a G-drive Slim from an Apple store to backup my computer before I install the new Mac OS X (10.6.3). My mac is currently at 10.5.8. Plugged it in and hit go and it stops every time.
Where do you hit "go"? There is no "go" button on any Time Machine menu.
After every time the "Available" capacity of the G-Drive decreases, even though there is nothing on it taking up space when I open it to check.
Open it how? Via the Finder, or the Time Machine browser (the "Star Wars" display), or something else?