Lion time machine - external drive spin up causing apps to crash

I have a 1TB external drive set up for time machine backups on my 27" iMac running Lion 10.7.3 that seems to be causing my Adobe CS 5.5 suite of apps (photoshop in partiucular) to crash as the drive spins up. If an adobe application or lion/time machine is asking the drive to spin up I have no idea, but it seems random, and when it does, the adobe app(s) freeze and the beach ball from **** just spins. All other applications remain uneffected which leads me to believe it's related to a scratch disk function of some sort. I've googled high and low to find an scrap on insight into this issue and have found nothing...

Few questions:

• Why does the time machine external drive randomly spin up even though there are no backup processes running?

• Why would an adobe app would need to access an external drive?

Before anyone says it, I know I can always just eject the drives, but I'd rather keep my backups running for obvious reasons. If a complete wipe and install is the only solution recommended by the doctor, I will. It's just maddening to regularly loose work. Any help is greatly appreciated!

iMac: Mid 2010 27"

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Processor 2.8 GHz Intel Core i5

Memory 8 GB 1333 MHz DDR3

Graphics ATI Radeon HD 5750 1024 MB

Software Mac OS X Lion 10.7.3 (11D50)

Adobe CS 5.5

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Photoshop CS5 / v12.1 x64

Illustrator CS5 / v15.1.0

InDesign CS5.5 / v7.5.2

External Drives

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Firewire800: 2TB Hitachi G-Drive: http://www.g-technology.com/products/g-drive.cfm

USB: 1TB Western Digital MyPassport 0730