I am using SDK 4.2 and i got the error message while opening any interface builder.
Assertion failure
Interface Builder encountered an
internal logic error. Choose
“Continue” to continue running
Interface Builder in an inconsistent
state. Choose “Crash” to halt
Interface Builder and file a bug with
Crash Reporter. Choosing “Crash” will
result in the loss of all unsaved
data.
Need help on this..
Not much to go on here.
Basically, IB is crashing. It could be the file you are opening or corrupted preferences. Try deleting preferences or opening a known good nib/xib file.