I had problems with my forward rolls as well. The instructers kept telling me to not "lock" my arms but neither was i to let it "slip in". argh..needless to say i was confused.
Turned out my problem was that i tried to roll on my side instead of OVER my head.(yeah it was a confidence issue).I was scared of wackin into the ground.
a)if you start rolling from a kneeling position instead of standing.learn how to walk b4 you fly.
b)if you were afraid of crashing into the ground like i was, it helps if you place the back of your hand on the floor facing you instead of rollin on the bottom of it. Since this way yor arm doesnt collapse too early and.
c)look at your instructor esp whenever he does something wrong. (i once saw my instructor roll over on his head in a technique gone wrong..yes it only happened once...but it told me
I)i wouldnt die if i crashed into the ground, that head roll looked very painful to me...
II)even the instructor does bad rolls sometimes!)
It gives you this confidence boost..oh well..=)
c)just tell yourself you already prepared for it in everyway you could. You would need to take this little risk in order to ever proceed any further in this art and that even if something bad happens,you wont die.
hope i helped