BACK UP YOUR WHOLE DRIVE ASAP!
My guess is that the SMART system has been tripped and reports one or more errors on one of the units in your RAID0. It is common for Windows to be set to monitor SMART error messages and flag them for attention. When you get a message like this, pay attention and find the problem and fix it.
Now, the major risk in RAID0 is that an error in one HDD unit means that entire file is useless. If you are lucky (yes, seems you are so far) there is only one error and only one file is affected, and you may not have tried to use it. But if more errors appear and one of them happens to be in a key area like a directory or allocation table, you could lose ALL of your data! So, back up NOW completely, then go looking for the source of the problem and decide whether to fix it and continue using the drive (with associated risks). Or, replace it and rebuild your array, then restore all data from your backup.