Currently, here are a few problems I have with the English-language spelling system:
"C" used as either the "k" sound or the "s" sound in such words a "canter" or "center"
"Q" used as the "k" sound (a totally superfluous letter, btw) in such words as "quick" or "quiet"
"K" used as a "silent letter" in such words as "knee", "knock", & "knife"
"P" used as a "silent letter" in such words as "pneumatic" & "pneumonia"
"G" used sometimes as a "j" sound and sometimes as a "hard g" sound in such words as "gentleman" and "good"
These are but a few examples, but there are others.