Can't say what this error means. You can also try stopping Spark and deleting your Spark profile (history will be lost), then start with a fresh profile.
C:\Users\username\AppData\Roaming\Spark
If you need your history, copy this folder:
C:\Users\username\AppData\Roaming\Spark\user\username@servername\transcripts
And copy it back after you start with a fresh profile.