What is your Race, Class and Level?
Human, Mage and 80.

What action bar mod do you use, if any?
Only DrDamage.

What is the expected output? What do you see instead?
Critical strike chance on fireball.
My crit chance without talents is 30.97%  plus [Playing with Fire] and [Critical Mass] which give 9 to all fire. And 3 from [Improved Scorch] and 5 from the glyhp of fireball on fireball only. Total 30.97+9+3+5 is 47.97 for fireball. But the tooltip says 53.97% crit on fireball.
Similarly on Pyroblast is should say 45.97 but it says 51.97

If this is an accuracy issue, what is your exact spec and your damage attributes? (For spells SP, for melee abilities AP/RAP, weapon etc.). Armory links are helpful.
http://eu.wowarmory.com/talent-calc.xml?cid=8&tal=23002503010003000000000000000000550320123033300530203003510000000000000000000000000000
The crit issue gives some errors on avarage damage but I will not nag about that because I think it is a followup error from the crit issue.

What version of DrDamage are you using?
1.6.8_release (Released: 2009/06/23) according to curse client.

Do you have an error log of what happened?
No and it is not really relevant in this case.

Please provide any additional information below.
The error is only on fire spells. Frost and arcane crit is correct.