What Can I Do to fix this gets real annoying.
How long have you had this modem for? Dlinks usually come with a 3 year warranty so ring up the help desk and tell them of your problems. It may be you would benefit from one of the new Thompson modems.
If you have done your 12month term you can also take advantage of this offer: http://www.telecom.co.nz/modemoffer
I have just upgraded to a Thompson TG585 and so far it's been good, however recently they changed my BB port / service area to a closer area, so I get good sync rates and my Dlink worked good also, but it was making this sharp ear piercing noise that would drive me to turn my router off every night.