Is anyone having issues accessing the shopping cart?
Afaik, some users are currently experiencing issues with parts of the NI website. It's a known issue/NI is already aware of it.
Until that's fixed, the best way for now is to get in touch with the customer support - they can fix that:
Yes, it's a known issue @Monochrome is right. For more info on the matter (when we get them):
NI Products page crashes / Blank pages during checkout