Hello Agnieszka,
When you re-installed the DBStudio after hardware migration, did you download and install the 64-bit version of the dbstudio ?
What is the version of java runtime installed on your machine ?
output of java -version
If you are a SAP customer, I would recommend you to create a CSS ticket and provide us with the WTS access to the server to analyze the issue in detail.
Regards, Yashwanth