How to resolve this deadlock error

You need to get more information in order to understand what's causing the deadlock. Usually the best way is to enable traceflag 1222 on the server. This can sometimes be difficult, especially on production machines, since it requires a restart. In the mean time, if you can reproduce the problem at will, try turning on a trace and capture the event Locks:Deadlock. That will show a graphical plan detailing the deadlock which will make it much easier to fix.

Check John Sansom's answer to a question here for links to aide you.

Deadlocks are generally caused by programming modules that do not perform the steps in the same order as each other. Module 1 locks table1 then table2 whereas module 2 does it in the reverse order. Neither module is able to continue because it has to wait on the resource.