I Guess this depends on how u have recorded the script.
Case1:
 if u have recorded the script with many google
pages(windows) open, as there are many windows open, QTP
identifies the ordinal identifier and stores it in the
repository.
So if we run the script, in this case you will not encounter
any problem even if there are hundreds of such windows.

Case2:
 If u have recorded the script with only one google window,
QTP will not store the Ordinal Identifier as it can clearly
identify the window we have specified.
So if we run the script, after opening many google windows,
QTP cannot identify the window in which it has to perform
the operations. so it returns an error.