Using USB hard drive and internet crashes router causing need to hard reboot

I was transferring files from my PC to the USB hard drive attached to my N900 router on USB1.  Whenever anyone tries to use the internet at the same time, the router completely crashes and requires a hard reboot.  You cannot access the router by //wdrouter at all.  This is a MAJOR issue. The settings for USB1 are on Share only.  I have disabled DLNA, iTunes and FTP just in case any of these selections were the cause. Any suggestions?

You can try with another USB memory or external hard drive to see if the same problem happens again. 

In speaking with a L2 rep at WD, they are replacing my router as I have several weird issues taht shouldn’t be happening. The device accessing the internet is an iPad2,while a PC is accessing the attached HDD. Time will tell after I get the replacement.