Error at start of Toad: "System.FormatException Input string was not in a correct format." (4377545)

Error at start of Toad: "System.FormatException Input string was not in a correct format."

Incorrect values or format found for the below numbers from the registry editor against the IBM data server client.

Below are parts of DB2 product standard signature format (VV.RR.MM.FF):

• VV Is the Version number.
• RR Is the Release number.
• MM Is the Modification number.
• FF Is the Fix Pack number.

Reinstall IBM DB2 client again. 
DB2 clients can be downloaded from here.