Woops..you mean the Tascam is an interface?  OK, then the problem must be your computer soundcard.  Either it is not compatible with the Tascam unit, or it does not have enough capability to handle the DSP (digital signal processing).  Check with Tascam which requirements they need for your computer to have, in order to work with the unit.  Worst comes to worst, all you will need to do is slip a different/better soundcard into your box or download some software for your computer.  Should be fixable. 

And...don't despair about computer recording until you've tried it.  For singer/songwriter/arranger activities it cannot be beat and is for the most part intuitive.  I was ready to toss in the hat and stick with my little stand alone unit, until I checked out Garage Band already in my computer.  I can do things much faster with GB; editing is a breeze and if you have a great take, just copy/paste to other parts of the song and ..you're done.   And GB is just entry level.  Sky is the limit with the amount of "toys" out there. 

Cubase, Digital Performer, Logic Pro, Sonar and Protools are all the same level of sophistication but are stronger/weaker in some aspects depending on what you're looking for.  I've read extensively on this, and it really boils down to what works best for your particular taste. 

However, one caveat emptor.  Only PT is the current industry "standard" in terms of portability.  So, you can open a PT session on any other studio with compatible ProTools anywhere in the world.   Talk is that Logic Pro (the Apple system) might take over as industry standard in about 5 years; I've heard that it has a very steep learning curve. For  ease of use...Digiperformer (comes with/married to MOTU). 

There's another one that is supposed to be good for live band recordings and very easy to use called Abelton LIVE.  The reviews are very good for that product.   I find that most people who use it are into rap, hip-hop, trance, electronica etc....uses a lot of keyboards and synth. 

Good luck.  Hope you can get your little Tascam workable.

Gene

P.S. I just checked.  That Tascam unit is superb and should handle anything. It's really portable, and sounds wonderful.  It uses USB 2.0 but will even handle USB 1.1 (which is usually a little too slow without latency problems) but...and here's the big "but", there is a zero latency thing they have built in, so you don't need firewire with this puppy.  Should sound pristine.   It matches best with Cubase LE, but will work superbly with all of the software I listed above...all of it.  Works on MAC or PC.    Soooo. the problem has gotta be your computer.  Phone someone from Tascam and trouble shoot the thing, but it sounds like a computer problem, possibly on the connection end.  You might have a "dud" unit, and they can exchange it out for ya'.   The unit is dynamite and 24bit/96 Khz so that is pretty much industry standard.  I might even get one myself....after reading about it.    And..their FW (Firewire) interfaces sound dynamite.  Thanks for the tip Herring!

http://www.tascam.com/Products/US-144.html