By using Recovery Scenario manager or by using a simple
If (..............Exists) Then

Do action......

End If

using exception handling we can handle the run time errors
they are three types in winrunner
1)tsl
2)object
3)pop-up

In qtp they are 4 types
1)pop-up window
2)object state
3)Test run error
4)application crash

We can handle runtime errors by using Exception Handling 
option in winrunner. In this we have 4 types of exceptions.
1. POPUP Exceptions
2. TSL Exceptions
3. Object Exceptions
4. Web Exceptions.

Correct me if i'm worng:)

1)Below are the trigger event Exceptions. we can hadle this 
type of run time errors Using Recovery scenario.

 pop-up windows,
 Object state,
 test run error
 application crash

Unexpected events, errors, and application crashes during a 
test run can
disrupt your test and distort test results. This is a 
problem particularly when
running tests unattended?the test is suspended until you 
perform the
action needed to recover.

By using Recovery Scenario manager 

Trigger Event
Recovery Operation
Post-Recovery Test Run Option

if this is wrong and letme know the correct ans