Two exceptions then run my applet

Following are two exceptions I got when run my applet. Then were in the run tab. I don't know when and why they were there. But I know they should not be there.

Exception "java.lang.ClassNotFoundException: com.intellij.codeInsight.m.bl"while constructing DataFlavor for: application/x-java-jvm-local-objectref; class=com.intellij.codeInsight.m.bl
Exception "java.lang.ClassNotFoundException: com.intellij.codeInsight.m.bk"while constructing DataFlavor for: application/x-java-jvm-local-objectref; class=com.intellij.codeInsight.m.bk