White Noise Help! -Newbie

I'm going to try not to overcomplicate this.

I have a Samson c03u microphone and I use Sonar LE to record. I don't record music, just my voice for screencasting tutorials. Frankly I am very un-audio-technical-savvy.

I have recorded about 40 different voice overs for my tutorials. During this time, everything went smooth, and when I played back, the white noise, background noise, hissing, etc was very minimal and the voice was clear. All of the sudden, today I open Sonar LE to record and there is this "shhhhhh" hissing background noise when I record. For example, before this change, I would record and when I wasn't speaking, the line in the middle was skinny and flat, now when I don't say anything there is a fatter, squigglier line with white noise. I record in the same place every day and the same environment. 

I usually export my audio file from Sonar LE and import into Audacity and use the noise removal tool and then export the finished product, but when I use noise removal now through Audacity it sounds muffled because the Sonar LE file had a lot of extra hiss for some reason.

Did I accidentally hit a button to make it do that? I even uninstalled and reinstalled the program and it didn't do anything. What setting or button or option can I use to get rid of this? 

-Extremely dense newbie