Is Christ Unstable? (Mark 11:12-25)

When we see Christ going into Jerusalem it seems that He has some anger management issues.  First, He curses a tree that did not bear fruit.  Second, he overturns tables in the temple and has what appears to be a tantrum.  How can these things make a credible point?  Why curse a tree out of anger and overturn the temple? Is the stress of the cross getting to Christ or is there more?