We had some issues of freezing (and BP crashing!) like this using certain UIA attributes (V6). Switching back to AA identifiers fixed it.
The other thing we did was switch the application model to 'external' and give a timeout value for an exception...
There's probably more elegant ways to do this (with proper escaping of text), but in the past I've used the 'chr()' function to represent my illegal characters and concatenated with the rest.
i.e to get a string With \backslashes\ I would put ""With...
Check out the 'command line options' page in the F1 help menu - you can run the resourcepc automate.exe with command line switches that authenticate it with a username and password.
@Saraansharya, if you needed to, I think you could accomplish this dynamically using the Utilitiy - Collection Manipulation VBO that's comes with BP. Specifically use 'get Collection Fields' on Coll B, and then 'rename Collection fields' on CollA. I...
In addition to the other responses, you can also access the pretty extensive Help menu within Blue Prism via F1. I've found it to be the best source of feature documentation