Try the following in order
Clear the java cache on the client machine.
Uninstall and then reinstall JRE on the client machine.
If the client has a version of JRE greater than the default version for your Spectrum install:Try the following in the order
1. Log into the OneClick web page as an ADMIN user
2. Click on the Administration link
3. Click on the OneClick Client Administration link
4. In the "Supported JRE Version" field, if the version of JRE installed on the client machine is greater than the one listed do one of the following:
a. Enter the JRE version installed on the client machine and click on the Add button
b. Click on the default version, check the "Allow new versions*" check box and then click on the Modify button
Check to make sure the client meets the OneClick client memory requirements:
1. Log into the OneClick web page as an ADMIN user
2. Click on the Administration link
3. Click on the OneClick Client Administration link
4. Note the Maximum "Java Memory Usage" value
5. Check the memory usage on the client machine to ensure the available memory is greater than the Maximum memory notes in step 4. If not, you need to increase the memory on the client machine.