So you are using not a locally installed ARIS Business Architect/Designer but a so called ARIS Web Client, downloaded from an ARIS Business Server, right?
If so, have you checked that on both computers the same Java version has been installed?
And that those machines are not using a not recommended Java version according to the Supported ARIS Platforms. Although that document is telling about ARIS 7.2, for ARIS 7.1 there's also a disadvise for Java 1.6.0 Update 19 or higher.
If that doesn't help, please report this issue to Global Support ARIS at email@example.com. They could run down with you a check list to exclude known issues.