Limitations of QTP 8.2

The limitations listed below are specifically for QTP 8.2:

Maximum worksheet size—65,536 rows by 256 columns
Column width—0 to 255 characters
Text length—16,383 characters
Formula length—1024 characters
Number precision—15 digits
Largest positive number—9.99999999999999E307
Largest negative number— -9.99999999999999E307
Smallest positive number—1E-307
Smallest negative number— -1E-307
Maximum number of names per workbook—Limited by available memory
Maximum length of name—255
Maximum length of format string—255
Maximum number of tables (workbooks)—Limited by system resources (windows and memory)

Theoritically we can say that there is no limitation in creating Actions in QTP.
But Microsoft Excel supports only 256 sheets. A seperate local Data sheet will be created for every action. Because there is a limitation in the no. of sheets in the Microsoft Excel, we can create 255 Actions. After creating 255 Actions in the QTP Test, an action will created but no Data sheet will be created for the Action which exceeded 255.

Generally test scripts will fail incase the system gets locked. This limitation is not limited to only QTP but happens with most of the tools. Reason behind this being, focus is shifted from the current execution process to OS.We have overcome this problem by getting Admin Pack installed for Windows XP. Admin pack basically enables the OS activites to operate independently of the ongoing process. Thus the execution process still continues to have focus even if the system gets locked. I suppose you could contact your sysadmin personnel to get more info on Admin Pack.