What script are you running?
which LR version are you using?
has this happend before with the same script?
has something changed in your system or AUT?
is this the only error message you are seeing?
are you running on a localhost LG (meaning is this a full installation) or on a remote LG?
"CPU usage exceeds 80%" easily happen when running TruClient script. IE/FF/Chrome browsers itself need take much CPU, it is out of Loadrunner control. You can get more information in here https://admhelp.microfocus.com/tc/en/12.53/Content/TruClient/procedures/_tc_t_how_to_calculate_load_generators.htm