Time Machine NOT SHOWING all backups

[ephmini]

I just purchased a MacMini 2.66 (older model), 4MB RAM a few weeks ago. I am running 10.6.4. I then bought a 1TB Iomega Minimax Firewire 800 drive and partitioned it to three partitions with GUID and Mac OS Journaled formatting on each. I have files on one partition, Time Machine backups of my MacMini and older data not being used as well.

Problem:
I go into Time Machine after waking the computer from a night of sleep mode. The Iomega is always on. Time Machine only shows the past two days of backups (by day, not hour) but when I actually go to the drive and look at the contents, all backups are showing for the past five days (since I started using the drive for TM). This morning it only showed Wednesday and Thursday, no Friday and it's now Saturday.

Fix that sucks but works okay:
I need to unmount the Iomega 1TB and then remount to see all backups in Time Machine again just fine.

Does anyone know how to fix this permanently? I don't want to use a third-party application if I don't have to as I like the TM interface.

Should I just not let my computer (MacMini) go to sleep and only sleep the display?

Thanks in advance.