Dear Mike
Generally, both iQ-VIEW and K-PACS can, of course, handle the display of ultrasound images.
As ultrasound images are often multiframe objects (i.e. image sequences), they can get pretty big, which could result in memory issues. I would suggest that first you check the log files of the application to see if any error messages come up when trying to display the images. You may also check if the images are compressed (in the original) and make sure that they are uncompressed when imported into iQ-VIEW or K-PACS. Lastly, you may use DICOM check tools to verify that the images you are trying to view aren't corrupted.
If you post some more details about what application (version) you use and what exactly does not work (steps to reproduce, error messages coming up, etc.), then the forum community may be able to give you more explicit advice.
In case you are running iQ-VIEW, please contact your local reseller for assistance.