Desktop Application – Select appropriate words for error levels

I am developing an open source system monitoring tool, ServiceMon, and I would be very happy if I chose the right words for a function.

The status of the system being monitored is presented with a named severity level. The level changes when the number of errors recorded within a certain period of time exceeds a certain threshold.

ServiceMon screenshots show the worsening error status
(Source: rightcalc.com)

I want to give each layer a name, which is used when configuring custom colors and thresholds. Ideally, I want to use meaningful adjectives instead of cold generic names like ErrorLevel1, ErrorLevel2, and so on.

I have so far:

Standard color | Number of errors | adjective
-------------------------------------------------- -
Green | 0 | operational
Yellow | 1 | Spirited
Orange | 2-9 | Unstable
Light red | 10-99 | Critical
Dark red | 100 or more | Dire

Are the words I have chosen appropriate? Can you imagine better alternatives?

Updated to explain the primary use case in more detail

I imagine that ServiceMon is mainly used as an "information spotlight" – a permanent presence in a room that instantly visually informs about the state of a system. Each ServiceMon instance is light weighted so that many can be viewed on one screen, each tracking a different system or aspect of the same system. For example, when a system is monitored for availability and Reaction time I would imagine that for each aspect a separate instance is run with its own thresholds.